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  <p style="border:none;color:windowtext;margin:0in 0in .0001pt;padding:0in;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
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  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;letter-spacing:-.1pt;">UNITED STATES</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;letter-spacing:-.1pt;">SECURITIES AND
  EXCHANGE COMMISSION</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">Washington, D.C. 20549</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;letter-spacing:-.1pt;">FORM&nbsp;8-K</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;letter-spacing:-.1pt;">CURRENT REPORT</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;letter-spacing:-.1pt;">PURSUANT TO SECTION&nbsp;13 OR 15(d)&nbsp;OF</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;letter-spacing:-.1pt;">THE SECURITIES EXCHANGE ACT OF 1934</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">Date of Report (Date of earliest event reported) May&nbsp;16,
  2008</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;letter-spacing:-.1pt;">MARKWEST
  ENERGY PARTNERS, L.P.</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">(Exact
  name of registrant as specified in its charter)</font></p>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
  
  <div align="center">
  
  <table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
   <tr>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">Delaware</font></b><font size="2" style="font-size:10.0pt;"><br>
    <font style="letter-spacing:-.1pt;">(State or other jurisdiction of</font><br>
    <font style="letter-spacing:-.1pt;">incorporation or organization)</font></font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;letter-spacing:-.1pt;">&nbsp;</font></b></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">001-31239</font></b><font size="2" style="font-size:10.0pt;"><br>
    <font style="letter-spacing:-.1pt;">(Commission File Number)</font></font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;letter-spacing:-.1pt;">&nbsp;</font></b></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">27-0005456</font></b><font size="2" style="font-size:10.0pt;"><br>
    <font style="letter-spacing:-.1pt;">(I.R.S. Employer</font><br>
    <font style="letter-spacing:-.1pt;">Identification Number)</font></font></p>
    </td>
   </tr>
   <tr>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">&nbsp;</font></b></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">&nbsp;</font></b></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">&nbsp;</font></b></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.0%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">&nbsp;</font></b></p>
    </td>
    <td width="32%" valign="top" style="padding:0in 0in 0in 0in;width:32.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">&nbsp;</font></b></p>
    </td>
   </tr>
   <tr>
    <td width="100%" colspan="5" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">1515 Arapahoe Street, Tower 2, Suite&nbsp;700,
    Denver, CO 80202</font></b></p>
    </td>
   </tr>
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    <td width="100%" colspan="5" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">(Address of principal executive offices)</font></p>
    </td>
   </tr>
  </table>
  
  </div>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">Registrant&#146;s
  telephone number, including area code: <b>303-925-9200</b></font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">Not Applicable.</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">(Former
  name or former address, if changed since last report.)</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">Check the appropriate box below if the Form&nbsp;8-K
  filing is intended to simultaneously satisfy the filing obligation of the
  registrant under any of the following provisions (see General Instruction A.2.
  below):</font></p>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
   <tr>
    <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
    </td>
    <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;letter-spacing:-.1pt;">o</font></p>
    </td>
    <td width="92%" valign="top" style="padding:0in 0in 0in 0in;width:92.56%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">Written Communications pursuant to Rule&nbsp;425 under
    the Securities Act (17 CFR 230.425)</font></p>
    </td>
   </tr>
   <tr>
    <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
    </td>
    <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;letter-spacing:-.1pt;">o</font></p>
    </td>
    <td width="92%" valign="top" style="padding:0in 0in 0in 0in;width:92.56%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">Soliciting material pursuant to Rule&nbsp;14a-12 under
    the Exchange Act (17 CFR 240.14a-12)</font></p>
    </td>
   </tr>
   <tr>
    <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
    </td>
    <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;letter-spacing:-.1pt;">o</font></p>
    </td>
    <td width="92%" valign="top" style="padding:0in 0in 0in 0in;width:92.56%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">Pre-Commencement communications pursuant to
    Rule&nbsp;14d-2(b)&nbsp;under the Exchange Act (17 CFR 240.14d-2(b))</font></p>
    </td>
   </tr>
   <tr>
    <td width="3%" valign="top" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
    </td>
    <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.72%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Wingdings" style="font-size:10.0pt;letter-spacing:-.1pt;">o</font></p>
    </td>
    <td width="92%" valign="top" style="padding:0in 0in 0in 0in;width:92.56%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">Pre-Commencement communications pursuant to
    Rule&nbsp;13e-4(c)&nbsp;under the Exchange Act (17 CFR 240.13e-4(c))</font></p>
    </td>
   </tr>
  </table>
  
  <div style="border:none;border-bottom:double windowtext 6.0pt;padding:0in 0in 0in 0in;">
  
  <p style="border:none;color:windowtext;margin:0in 0in .0001pt;padding:0in;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  </div>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <div style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
  
  </div>
  <!-- SEQ.=1,FOLIO='',FILE='C:\JMS\brosent\08-14811-1\task2951700\14811-1-ba.htm',USER='brosent',CD='May 20 20:38 2008' -->
  
  
  <br clear="all" style="page-break-before:always;">
  
  
  <div>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">ITEM&nbsp;7.01 &nbsp;&nbsp;Regulation FD</font></b></p>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">In accordance with General
  Instruction B.2 of Form&nbsp;8-K, the following information in this Current
  Report on Form&nbsp;8-K (including the exhibit) is furnished pursuant to Item
  7.01 and shall not be deemed to be &#147;filed&#148; for the purpose of Section&nbsp;18
  of the Securities Exchange Act of 1934 or otherwise subject to the liabilities
  of that section.&nbsp; This Current Report will not be deemed an admission as
  to the materiality of any information in the report that is required to be
  disclosed solely by Regulation FD.</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">On May&nbsp;16, 2008, MarkWest
  Energy Partners, L.P. (the &#147;Partnership&#148;) announced that Frank Semple,
  President and Chief Executive Officer, will present at the 2008 Master Limited
  Partnership Investor Conference on May&nbsp;21, 2008, at the Crowne Plaza Times
  Square hotel in New York City.&#160; A press
  release announcing this presentation is included as Exhibit&nbsp;99.1.</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">The information included with
  this Current Report as Exhibit&nbsp;99.2 includes graphic images or slides used
  in the presentation.&nbsp; These slides are available for viewing at our
  website, www.markwest.com, although we reserve the right to discontinue that
  availability at any time.</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">&nbsp;</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">This presentation utilizes the Non-GAAP
  financial measures of Adjusted EBITDA and Distributable Cash Flow.&#160; We define Adjusted EBITDA as net income or
  loss before interest, provision for income taxes, depreciation and amortization
  expense, impairment expense gain/loss on disposal of property, plant and
  equipment, non-cash compensation expense, and non-cash derivative activity.&#160; Adjusted EBITDA is not a measure of
  performance calculated in accordance with GAAP, and should not be considered in
  isolation or as a substitute for net income, income from operations, or cash
  flow as reflected in our financial statements. Adjusted EBITDA is presented
  because such information is relevant and is used by management, industry
  analysts, investors, lenders, and rating agencies to assess the financial
  performance and operating results of our fundamental business activities.
  Management believes that the presentation of Adjusted EBITDA is useful to
  lenders and investors because of its use in the midstream natural gas industry
  and for master limited partnerships as an indicator of the strength and
  performance of our ongoing business operations. Additionally, management
  believes that Adjusted EBITDA provides additional and useful information to our
  investors for trending, analyzing, and benchmarking our operating results from
  period to period as compared to other companies that may have different
  financing and capital structures. The presentation of Adjusted EBITDA allows
  investors to view our performance in a manner similar to the methods used by
  management and provides additional insight to our operating results.&#160; In general, we define Distributable Cash Flow
  as net income or loss plus (i)&nbsp;depreciation, amortization, and accretion
  expense; (ii)&nbsp;non-cash earnings from unconsolidated affiliates; (iii)&nbsp;contributions
  to unconsolidated affiliates net of expansion capital expenditures; (iv)&nbsp;non-cash
  compensation expense; (v)&nbsp;non-cash derivative activity; (vi)&nbsp;gains
  and losses on the sale of assets; and (vii)&nbsp;the subtraction of sustaining
  capital expenditures. Distributable Cash Flow is a significant liquidity metric
  used by our senior management to compare basic cash flows generated by us to
  the cash distributions we expect to pay partners. Distributable cash flow is
  also an important Non-GAAP financial measure for our limited partners since it
  serves as an indicator of our success in providing a cash return on investment.
  Distributable cash flow is also a quantitative standard used by the investment
  community with respect to publicly traded partnerships such as ours because the
  value of a partnership unit is in part measured by its yield (which in turn is
  based on the amount of cash distributions a partnership pays to a unitholder).
  The GAAP measure most directly comparable to Distributable Cash Flow and
  Adjusted EBITDA is net income.&#160; Please
  see the presentation for our calculations of Adjusted EBITDA and Distributable
  Cash Flow along with the appropriate reconciliations.</font></p>
  
  <p style="color:#041879;margin:0in 0in .0001pt;"><font size="2" color="black" face="Times New Roman" style="color:windowtext;font-size:10.0pt;">&nbsp;</font></p>
  
  <h1 style="color:windowtext;font-style:italic;font-weight:normal;margin:0in 0in .0001pt .5in;page-break-after:avoid;"><i><font size="2" face="Times New Roman" style="font-size:10.0pt;">Cautionary Statements</font></i></h1>
  
  <h1 style="color:windowtext;font-style:italic;font-weight:normal;margin:0in 0in .0001pt .5in;page-break-after:avoid;"><i><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></i></h1>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">This presentation includes &#147;forward-looking
  statements.&#148;&#160; All statements other than
  statements of historical facts included or incorporated herein may constitute
  forward-looking statements.&#160; Actual
  results could vary significantly from those expressed or implied in such
  statements and are subject to a number of risks and uncertainties.&#160; Although we believe that the expectations
  reflected in the forward-looking statements are reasonable, we can give no
  assurance that such expectations will prove to be correct.&#160; The forward-looking statements involve risks
  and uncertainties that affect our operations, financial performance and other
  factors as discussed in our filings with the Securities and Exchange
  Commission.&#160; Among the factors that could
  cause results to differ materially are those risks discussed in our Form&nbsp;10-K
  for the year ended December&nbsp;31, 2007, as amended, and our Quarterly Report
  on Form&nbsp;10-Q, each as filed with the SEC.&#160;
  You are urged to carefully review and consider the cautionary statements
  and other disclosures made in those filings, specifically those under the
  heading &#147;Risk Factors.&#148;</font></p>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:center;text-autospace:none;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2</font></p>
  
  <div align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:left;text-autospace:none;text-indent:0in;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
  
  </div>
  <!-- SEQ.=1,FOLIO='2',FILE='C:\JMS\brosent\08-14811-1\task2951700\14811-1-ba.htm',USER='brosent',CD='May 20 20:38 2008' -->
  
  
  <br clear="all" style="page-break-before:always;">
  
  
  <div style="font-family:Times New Roman;">
  
  <p align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:left;text-autospace:none;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:left;text-autospace:none;text-indent:0in;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">ITEM 9.01.
  Financial Statements and Exhibits</font></b></p>
  
  <p align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt .25in;text-align:left;text-autospace:none;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <table border="0" cellspacing="0" cellpadding="0" width="96%" style="border-collapse:collapse;margin-left:.25in;width:96.68%;">
   <tr>
    <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(d)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Exhibits.</font></p>
    </td>
   </tr>
   <tr>
    <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
    </td>
   </tr>
   <tr>
    <td width="9%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:9.06%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Exhibit&nbsp;No.</font></b></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.74%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
    </td>
    <td width="88%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:88.2%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Description of Exhibit</font></b></p>
    </td>
   </tr>
   <tr>
    <td width="9%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:9.06%;">
    <p align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:left;text-autospace:none;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.74%;">
    <p align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:left;text-autospace:none;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="88%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:88.2%;">
    <p align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:left;text-autospace:none;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="9%" valign="top" style="padding:0in 0in 0in 0in;width:9.06%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">99.1</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.74%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="88%" valign="top" style="padding:0in 0in 0in 0in;width:88.2%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Press
    release dated May&nbsp;16, 2008 announcing MarkWest Energy Partners to present
    at the </font><font size="2" style="font-size:10.0pt;">2008 Master
    Limited Partnership Investor Conference</font><font size="2" style="font-size:10.0pt;">.</font></p>
    </td>
   </tr>
   <tr>
    <td width="9%" valign="top" style="padding:0in 0in 0in 0in;width:9.06%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.74%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="88%" valign="top" style="padding:0in 0in 0in 0in;width:88.2%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="9%" valign="top" style="padding:0in 0in 0in 0in;width:9.06%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">99.2</font></p>
    </td>
    <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.74%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="88%" valign="top" style="padding:0in 0in 0in 0in;width:88.2%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Investor presentation
    to be presented May&nbsp;21, 2008 in New York City.</font></p>
    </td>
   </tr>
  </table>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3</font></p>
  
  <div style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><hr size="3" width="100%" noshade color="#010101" align="left"></div>
  
  </div>
  <!-- SEQ.=1,FOLIO='3',FILE='C:\JMS\brosent\08-14811-1\task2951700\14811-1-ba.htm',USER='brosent',CD='May 20 20:38 2008' -->
  
  
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  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;letter-spacing:-.1pt;">SIGNATURE</font></b></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="left" style="color:windowtext;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt;text-align:left;text-autospace:none;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the requirements of the
  Securities and Exchange Act of 1934, the Registrant has duly caused this report
  to be signed on its behalf by the undersigned, thereunto duly authorized.</font></p>
  
  <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
  
  <table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
    </td>
    <td width="47%" colspan="4" valign="top" style="padding:0in 0in 0in 0in;width:47.18%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">MARKWEST
    ENERGY PARTNERS, L.P.</font></p>
    </td>
   </tr>
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="28%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:28.42%;">
    <p align="right" style="color:windowtext;margin:0in 0in .0001pt 1.0in;text-align:right;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">(Registrant)</font></p>
    </td>
    <td width="18%" valign="top" style="padding:0in 0in 0in 0in;width:18.76%;">
    <p style="color:windowtext;margin:0in 0in .0001pt 1.0in;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="47%" colspan="4" valign="top" style="padding:0in 0in 0in 0in;width:47.18%;">
    <p style="color:windowtext;margin:0in 0in .0001pt 1.0in;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="5%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:5.36%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:</font></p>
    </td>
    <td width="41%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:41.84%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Markwest Energy GP, L.L.C.,</font></p>
    </td>
   </tr>
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="5%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:5.36%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
    </td>
    <td width="41%" colspan="2" valign="top" style="padding:0in 0in 0in 0in;width:41.84%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">its General Partner</font></p>
    </td>
   </tr>
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
    <td width="47%" colspan="4" valign="top" style="padding:0in 0in 0in 0in;width:47.18%;">
    <p style="color:windowtext;margin:0in 0in .0001pt 1.0in;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="100%" colspan="5" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
    </td>
   </tr>
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">Date:
    &nbsp;May&nbsp;20, 2008 </font></p>
    </td>
    <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.26%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">By:</font></p>
    </td>
    <td width="41%" colspan="3" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:41.92%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">/s/ C. CORWIN BROMLEY</font></p>
    </td>
   </tr>
   <tr>
    <td width="52%" valign="top" style="padding:0in 0in 0in 0in;width:52.82%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:1.0pt;letter-spacing:-.1pt;">&nbsp;</font></p>
    </td>
    <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.26%;">
    <p style="color:windowtext;margin:0in 0in .0001pt;text-autospace:none;"><i><font size="2" face="Times New Roman" style="font-size:1.0pt;font-style:italic;letter-spacing:-.1pt;">&nbsp;</font></i></p>
    </td>
    <td width="41%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:41.92%;">
    <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:-.1pt;">C. Corwin Bromley</font><font size="2" style="font-size:10.0pt;"><br>
    </font><i><font size="2" style="font-size:10.0pt;font-style:italic;letter-spacing:-.1pt;">Senior Vice President, General Counsel</font></i></p>
    </td>
   </tr>
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    <td width="39" style="border:none;"></td>
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    <td width="140" style="border:none;"></td>
   </tr>
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  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  
  <p align="center" style="color:windowtext;margin:0in 0in .0001pt;text-align:center;text-autospace:none;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4</font></p>
  
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metadata_documents: [{"type": "8-K", "sequence": "1", "filename": "a08-14811_18k.htm", "description": "8-K", "secsgml_size_bytes": 38992}]
metadata_filer: {"company-data": {"conformed-name": "MARKWEST ENERGY PARTNERS L P", "cik": "0001166036", "assigned-sic": "1311", "irs-number": "270005456", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-31239", "film-number": "08850416"}, "business-address": {"street1": "1515 ARAPAHOE STREET", "street2": "TOWER 2, SUITE 700", "city": "DENVER", "state": "CO", "zip": "80202-2126", "phone": "303-925-9200"}, "mail-address": {"street1": "1515 ARAPAHOE STREET", "street2": "TOWER 2, SUITE 700", "city": "DENVER", "state": "CO", "zip": "80202-2126"}}
text: UNITED STATES
  SECURITIES AND
  EXCHANGE COMMISSION
  Washington, D.C. 20549
  FORM 8-K
  CURRENT REPORT
  PURSUANT TO SECTION 13 OR 15(d) OF
  THE SECURITIES EXCHANGE ACT OF 1934
  Date of Report (Date of earliest event reported) May 16,
  2008
  MARKWEST
  ENERGY PARTNERS, L.P.
  (Exact
  name of registrant as specified in its charter)
  Delaware
  (State or other jurisdiction of
  incorporation or organization)
  001-31239
  (Commission File Number)
  27-0005456
  (I.R.S. Employer
  Identification Number)
  1515 Arapahoe Street, Tower 2, Suite 700,
    Denver, CO 80202
  (Address of principal executive offices)
  Registrant's
  telephone number, including area code:
  303-925-9200
  Not Applicable.
  (Former
  name or former address, if changed since last report.)
  Check the appropriate box below if the Form 8-K
  filing is intended to simultaneously satisfy the filing obligation of the
  registrant under any of the following provisions (see General Instruction A.2.
  below):
  o
  Written Communications pursuant to Rule 425 under
    the Securities Act (17 CFR 230.425)
  o
  Soliciting material pursuant to Rule 14a-12 under
    the Exchange Act (17 CFR 240.14a-12)
  o
  Pre-Commencement communications pursuant to
    Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
  o
  Pre-Commencement communications pursuant to
    Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
  ITEM 7.01   Regulation FD
  In accordance with General
  Instruction B.2 of Form 8-K, the following information in this Current
  Report on Form 8-K (including the exhibit) is furnished pursuant to Item
  7.01 and shall not be deemed to be "filed" for the purpose of Section 18
  of the Securities Exchange Act of 1934 or otherwise subject to the liabilities
  of that section.  This Current Report will not be deemed an admission as
  to the materiality of any information in the report that is required to be
  disclosed solely by Regulation FD.
  On May 16, 2008, MarkWest
  Energy Partners, L.P. (the "Partnership") announced that Frank Semple,
  President and Chief Executive Officer, will present at the 2008 Master Limited
  Partnership Investor Conference on May 21, 2008, at the Crowne Plaza Times
  Square hotel in New York City.  A press
  release announcing this presentation is included as Exhibit 99.1.
  The information included with
  this Current Report as Exhibit 99.2 includes graphic images or slides used
  in the presentation.  These slides are available for viewing at our
  website, www.markwest.com, although we reserve the right to discontinue that
  availability at any time.
  This presentation utilizes the Non-GAAP
  financial measures of Adjusted EBITDA and Distributable Cash Flow.  We define Adjusted EBITDA as net income or
  loss before interest, provision for income taxes, depreciation and amortization
  expense, impairment expense gain/loss on disposal of property, plant and
  equipment, non-cash compensation expense, and non-cash derivative activity.  Adjusted EBITDA is not a measure of
  performance calculated in accordance with GAAP, and should not be considered in
  isolation or as a substitute for net income, income from operations, or cash
  flow as reflected in our financial statements. Adjusted EBITDA is presented
  because such information is relevant and is used by management, industry
  analysts, investors, lenders, and rating agencies to assess the financial
  performance and operating results of our fundamental business activities.
  Management believes that the presentation of Adjusted EBITDA is useful to
  lenders and investors because of its use in the midstream natural gas industry
  and for master limited partnerships as an indicator of the strength and
  performance of our ongoing business operations. Additionally, management
  believes that Adjusted EBITDA provides additional and useful information to our
  investors for trending, analyzing, and benchmarking our operating results from
  period to period as compared to other companies that may have different
  financing and capital structures. The presentation of Adjusted EBITDA allows
  investors to view our performance in a manner similar to the methods used by
  management and provides additional insight to our operating results.  In general, we define Distributable Cash Flow
  as net income or loss plus (i) depreciation, amortization, and accretion
  expense; (ii) non-cash earnings from unconsolidated affiliates; (iii) contributions
  to unconsolidated affiliates net of expansion capital expenditures; (iv) non-cash
  compensation expense; (v) non-cash derivative activity; (vi) gains
  and losses on the sale of assets; and (vii) the subtraction of sustaining
  capital expenditures. Distributable Cash Flow is a significant liquidity metric
  used by our senior management to compare basic cash flows generated by us to
  the cash distributions we expect to pay partners. Distributable cash flow is
  also an important Non-GAAP financial measure for our limited partners since it
  serves as an indicator of our success in providing a cash return on investment.
  Distributable cash flow is also a quantitative standard used by the investment
  community with respect to publicly traded partnerships such as ours because the
  value of a partnership unit is in part measured by its yield (which in turn is
  based on the amount of cash distributions a partnership pays to a unitholder).
  The GAAP measure most directly comparable to Distributable Cash Flow and
  Adjusted EBITDA is net income.  Please
  see the presentation for our calculations of Adjusted EBITDA and Distributable
  Cash Flow along with the appropriate reconciliations.
  Cautionary Statements
  This presentation includes "forward-looking
  statements."  All statements other than
  statements of historical facts included or incorporated herein may constitute
  forward-looking statements.  Actual
  results could vary significantly from those expressed or implied in such
  statements and are subject to a number of risks and uncertainties.  Although we believe that the expectations
  reflected in the forward-looking statements are reasonable, we can give no
  assurance that such expectations will prove to be correct.  The forward-looking statements involve risks
  and uncertainties that affect our operations, financial performance and other
  factors as discussed in our filings with the Securities and Exchange
  Commission.  Among the factors that could
  cause results to differ materially are those risks discussed in our Form 10-K
  for the year ended December 31, 2007, as amended, and our Quarterly Report
  on Form 10-Q, each as filed with the SEC. 
  You are urged to carefully review and consider the cautionary statements
  and other disclosures made in those filings, specifically those under the
  heading "Risk Factors."
  2
  ITEM 9.01.
  Financial Statements and Exhibits
  (d)        Exhibits.
  Exhibit No.
  Description of Exhibit
  99.1
  Press
    release dated May 16, 2008 announcing MarkWest Energy Partners to present
    at the
  2008 Master
    Limited Partnership Investor Conference
  .
  99.2
  Investor presentation
    to be presented May 21, 2008 in New York City.
  3
  SIGNATURE
  Pursuant to the requirements of the
  Securities and Exchange Act of 1934, the Registrant has duly caused this report
  to be signed on its behalf by the undersigned, thereunto duly authorized.
  MARKWEST
    ENERGY PARTNERS, L.P.
  (Registrant)
  By:
  Markwest Energy GP, L.L.C.,
  its General Partner
  Date:
     May 20, 2008
  By:
  /s/ C. CORWIN BROMLEY
  C. Corwin Bromley
  Senior Vice President, General Counsel
  4