UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                              --------------------

                                    FORM S-8

             Registration Statement under the Securities Act of 1933
                              --------------------


                           MOLECULAR BIOSYSTEMS, INC.
             (Exact name of Registrant as specified in its charter)

                               Delaware 36-3078632
                  (State or other jurisdiction (I.R.S. Employer
            of incorporation or organization) Identification Number)

                            10030 Barnes Canyon Road
                           San Diego, California 92121
                    (Address of principal executive offices)

                           Molecular Biosystems, Inc.
                             1993 Stock Option Plan
                            (Full title of the plan)

                                Bobba Venkatadri
                      President and Chief Executive Officer
                           Molecular Biosystems, Inc.
                            10030 Barnes Canyon Road
                           San Diego, California 92121
                                 (619) 452-0681
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)



------------- ------------  ---------------   -----------------  ---------------
  Title of    Amount To Be  Proposed Maximum   Proposed Maximum     Amount of
 Securities    Registered    Offering Price       Aggregate       Registration
  To Be                       Per Share(1)        Offering           Fee(1)     
 Registered                                        Price(1)           
------------- ------------  ---------------   -----------------  ---------------
------------- ------------  ---------------   -----------------  ---------------

Common Stock,
  par value     750,000
$.01 per share  shares          $9.06           $6,795,000.00       $2,059.09

------------- ------------  ---------------   -----------------  ---------------

(1) Computed pursuant to Rule 457(c), in accordance with Rule 457(h)(1), on
the basis of the average of the high and low sales prices of a share of
the Registrant's Common Stock reported on the New York Stock Exchange,
Inc. on September 2, 1997.


<PAGE>


                 INCORPORATION OF EARLIER REGISTRATION STATEMENT


       This  Registration  Statement  on Form S-8 is filed in respect of 750,000
shares of the Registrant's Common Stock, par value $.01 per share, issuable upon
the exercise of options granted or to be granted under the Molecular Biosystems,
Inc. 1993 Stock Option Plan (the "Plan").

       An earlier Registration Statement on Form S-8, Registration No. 33-78572,
is  effective in respect of 2,500,000  shares of the  Registrant's  Common Stock
issuable  upon the exercise of options  granted or to be granted under the Plan.
In  accordance  with  General   Instruction  E   ("Registration   of  Additional
Securities")  to Form S-8, the contents of this earlier  Registration  Statement
are incorporated by reference.

       The Registrant's response to Item 5 in the earlier Registration Statement
is, however, updated as follows:

Item 5.    Interests of Named Experts and Counsel

       The  legality of the Shares is being  passed upon for the  Registrant  by
Johnson and Colmar, 300 South Wacker Drive, Suite 1000, Chicago, Illinois 60606,
who serve as the Registrant's outside general counsel.

       Craig P.  Colmar,  who is a partner of Johnson  and  Colmar,  is also the
Company's Secretary.  Mr. Colmar owns of record and beneficially 1,000 shares of
Common  Stock,  and other  partners  of  Johnson  and  Colmar  own of record and
beneficially  a further 1,200 shares.  In addition,  Mr. Colmar holds options to
purchase  35,750 shares of the  Registrant's  Common Stock.  These stock options
were granted at option prices equal to the fair market value of the Registrant's
Common Stock on the dates of grant.

Item 8.    Exhibits

  4.1    First Amendment to Molecular Biosystems, Inc. 1993 Stock Option Plan

  5.1    Opinion of Johnson and Colmar

 23.1    Consent of Arthur Andersen LLP

 23.2    Consent of Johnson and Colmar (filed as part of Exhibit 5.1)

 24.1    Power of attorney  (included under the caption "Power of Attorney"
on page 3).



<PAGE>


                                   SIGNATURES

       Pursuant to the  requirements  of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the  requirements  for  filing  on  Form  S-8 and has  duly  caused  this
Registration Statement to be signed on its behalf by the undersigned,  thereunto
duly authorized,  in the City of San Diego, State of California, on September 8,
1997.


                                                     Molecular Biosystems, Inc.


                                                     By:  /s/ BOBBA VENKATADRI
                                                          Bobba Venkatadri
                                                          President and Chief
                                                            Executive Officer

                                Power of Attorney

       Each  person  whose  signature  appears  below who is then an  officer or
director of the Registrant  authorizes  Bobba Venkatadri and Gerard A. Wills, or
either of them, with full power of substitution and  resubstitution,  to sign in
his name and to file any  amendments  (including  post-effective  amendments) to
this Registration Statement) and all related documents necessary or advisable to
enable the Registrant to comply with the Securities Act of 1933, as amended,  in
connection  with the  registration  of the securities  which are covered by this
Registration  Statement,   which  amendments  may  make  such  changes  in  this
Registration  Statement (as it may be so amended) as Bobba  Venkatadri or Gerard
A. Wills or either of them,  may deem  appropriate,  and to do and  perform  all
other related acts and things necessary to be done.

       Pursuant to the  requirements  of the Securities Act of 1933, as amended,
this  Registration  Statement has been signed below by the following  persons in
the capacities and on the dates indicated.


<PAGE>





Name                                Title                            Date



/s/ BOBBA VENKATADRI         President, Chief Executive        September 8, 1997
Bobba Venkatadri             Officer and a Director 
                             (Principal Executive Officer)


/s/ GERARD A. WILLS          Vice President, Finance and Chief September 8, 1997
Gerard A. Wills              Financial Officer (Principal
                             Financial and Accounting Officer)

/s/ KENNETH J. WIDDER, M.D   Chairman of the                   September 8, 1997
Kenneth J. Widder, M.D.      Board of Directors


/s/ DAVID W. BARRY, M.D.     Director                          September 8, 1997
David W. Barry, M.D.

/s/ ROBERT W. BRIGHTFELT     Director                          September 8, 1997
Robert W. Brightfelt

/s/ CHARLES C. EDWARDS, M.D. Director                          September 8, 1997
Charles C. Edwards, M.D.

/s/ JERRY T. JACKSON         Director                          September 8, 1997
Jerry T. Jackson

/s/ GORDON C. LUCE           Director                          September 8, 1997
Gordon C. Luce

/s/ DAVID RUBINFIEN          Director                          September 8, 1997
David Rubinfien


<PAGE>


                                Index to Exhibits



       Exhibit  Description                                         Sequentially
       Number                                                         Numbered
                                                                        Page
         4.1    First Amendment to Molecular Biosystems, Inc.
                1993 Stock Option Plan                                    6
     
         5.1    Opinion of Johnson and Colmar                             7

        23.1    Consent of Arthur Andersen LLP                            9

        23.2    Consent of Johnson and Colmar
                (filed as part of Exhibit 5.1)                            -
     
        24.1    Power of Attorney (included under the caption
                "Power of Attorney" on  page 3)                           -
                      


<PAGE>
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{"company-data": {"conformed-name": "MOLECULAR BIOSYSTEMS INC", "cik": "0000719598", "assigned-sic": "2835", "irs-number": "363078632", "state-of-incorporation": "DE", "fiscal-year-end": "0331"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-35633", "film-number": "97680669"}, "business-address": {"street1": "10030 BARNES CANYON RD", "city": "SAN DIEGO", "state": "CA", "zip": "92121-2789", "phone": "6198242200"}, "mail-address": {"street1": "10030 BARNES CANYON ROAD", "city": "SAN DIEGO", "state": "CA", "zip": "92121"}}
UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                              --------------------

                                    FORM S-8

             Registration Statement under the Securities Act of 1933
                              --------------------

                           MOLECULAR BIOSYSTEMS, INC.
             (Exact name of Registrant as specified in its charter)

                               Delaware 36-3078632
                  (State or other jurisdiction (I.R.S. Employer
            of incorporation or organization) Identification Number)

                            10030 Barnes Canyon Road
                           San Diego, California 92121
                    (Address of principal executive offices)

                           Molecular Biosystems, Inc.
                             1993 Stock Option Plan
                            (Full title of the plan)

                                Bobba Venkatadri
                      President and Chief Executive Officer
                           Molecular Biosystems, Inc.
                            10030 Barnes Canyon Road
                           San Diego, California 92121
                                 (619) 452-0681
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

------------- ------------  ---------------   -----------------  ---------------
  Title of    Amount To Be  Proposed Maximum   Proposed Maximum     Amount of
 Securities    Registered    Offering Price       Aggregate       Registration
  To Be                       Per Share(1)        Offering           Fee(1)     
 Registered                                        Price(1)           
------------- ------------  ---------------   -----------------  ---------------
------------- ------------  ---------------   -----------------  ---------------

Common Stock,
  par value     750,000
$.01 per share  shares          $9.06           $6,795,000.00       $2,059.09

------------- ------------  ---------------   -----------------  ---------------

(1) Computed pursuant to Rule 457(c), in accordance with Rule 457(h)(1), on
the basis of the average of the high and low sales prices of a share of
the Registrant's Common Stock reported on the New York Stock Exchange,
Inc. on September 2, 1997.
INCORPORATION OF EARLIER REGISTRATION STATEMENT

       This  Registration  Statement  on Form S-8 is filed in respect of 750,000
shares of the Registrant's Common Stock, par value $.01 per share, issuable upon
the exercise of options granted or to be granted under the Molecular Biosystems,
Inc. 1993 Stock Option Plan (the "Plan").

       An earlier Registration Statement on Form S-8, Registration No. 33-78572,
is  effective in respect of 2,500,000  shares of the  Registrant's  Common Stock
issuable  upon the exercise of options  granted or to be granted under the Plan.
In  accordance  with  General   Instruction  E   ("Registration   of  Additional
Securities")  to Form S-8, the contents of this earlier  Registration  Statement
are incorporated by reference.

       The Registrant's response to Item 5 in the earlier Registration Statement
is, however, updated as follows:

Item 5.    Interests of Named Experts and Counsel

       The  legality of the Shares is being  passed upon for the  Registrant  by
Johnson and Colmar, 300 South Wacker Drive, Suite 1000, Chicago, Illinois 60606,
who serve as the Registrant's outside general counsel.

       Craig P.  Colmar,  who is a partner of Johnson  and  Colmar,  is also the
Company's Secretary.  Mr. Colmar owns of record and beneficially 1,000 shares of
Common  Stock,  and other  partners  of  Johnson  and  Colmar  own of record and
beneficially  a further 1,200 shares.  In addition,  Mr. Colmar holds options to
purchase  35,750 shares of the  Registrant's  Common Stock.  These stock options
were granted at option prices equal to the fair market value of the Registrant's
Common Stock on the dates of grant.

Item 8.    Exhibits

  4.1    First Amendment to Molecular Biosystems, Inc. 1993 Stock Option Plan

  5.1    Opinion of Johnson and Colmar

 23.1    Consent of Arthur Andersen LLP

 23.2    Consent of Johnson and Colmar (filed as part of Exhibit 5.1)

 24.1    Power of attorney  (included under the caption "Power of Attorney"
on page 3).
SIGNATURES

       Pursuant to the  requirements  of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the  requirements  for  filing  on  Form  S-8 and has  duly  caused  this
Registration Statement to be signed on its behalf by the undersigned,  thereunto
duly authorized,  in the City of San Diego, State of California, on September 8,
1997.

                                                     Molecular Biosystems, Inc.

                                                     By:  /s/ BOBBA VENKATADRI
                                                          Bobba Venkatadri
                                                          President and Chief
                                                            Executive Officer

                                Power of Attorney

       Each  person  whose  signature  appears  below who is then an  officer or
director of the Registrant  authorizes  Bobba Venkatadri and Gerard A. Wills, or
either of them, with full power of substitution and  resubstitution,  to sign in
his name and to file any  amendments  (including  post-effective  amendments) to
this Registration Statement) and all related documents necessary or advisable to
enable the Registrant to comply with the Securities Act of 1933, as amended,  in
connection  with the  registration  of the securities  which are covered by this
Registration  Statement,   which  amendments  may  make  such  changes  in  this
Registration  Statement (as it may be so amended) as Bobba  Venkatadri or Gerard
A. Wills or either of them,  may deem  appropriate,  and to do and  perform  all
other related acts and things necessary to be done.

       Pursuant to the  requirements  of the Securities Act of 1933, as amended,
this  Registration  Statement has been signed below by the following  persons in
the capacities and on the dates indicated.
Name                                Title                            Date

/s/ BOBBA VENKATADRI         President, Chief Executive        September 8, 1997
Bobba Venkatadri             Officer and a Director 
                             (Principal Executive Officer)

/s/ GERARD A. WILLS          Vice President, Finance and Chief September 8, 1997
Gerard A. Wills              Financial Officer (Principal
                             Financial and Accounting Officer)

/s/ KENNETH J. WIDDER, M.D   Chairman of the                   September 8, 1997
Kenneth J. Widder, M.D.      Board of Directors

/s/ DAVID W. BARRY, M.D.     Director                          September 8, 1997
David W. Barry, M.D.

/s/ ROBERT W. BRIGHTFELT     Director                          September 8, 1997
Robert W. Brightfelt

/s/ CHARLES C. EDWARDS, M.D. Director                          September 8, 1997
Charles C. Edwards, M.D.

/s/ JERRY T. JACKSON         Director                          September 8, 1997
Jerry T. Jackson

/s/ GORDON C. LUCE           Director                          September 8, 1997
Gordon C. Luce

/s/ DAVID RUBINFIEN          Director                          September 8, 1997
David Rubinfien
Index to Exhibits

       Exhibit  Description                                         Sequentially
       Number                                                         Numbered
                                                                        Page
         4.1    First Amendment to Molecular Biosystems, Inc.
                1993 Stock Option Plan                                    6
     
         5.1    Opinion of Johnson and Colmar                             7

        23.1    Consent of Arthur Andersen LLP                            9

        23.2    Consent of Johnson and Colmar
                (filed as part of Exhibit 5.1)                            -
     
        24.1    Power of Attorney (included under the caption
                "Power of Attorney" on  page 3)                           -