<PAGE>   1
      As filed with the Securities and Exchange Commission on July 24, 1998
                              Subject to amendment.
                                                           Registration No. 33-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

                         NOVAMETRIX MEDICAL SYSTEMS INC.
             (Exact name of registrant as specified in its charter)

            DELAWARE                                             06-0977422
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)

                               5 Technology Drive
                         Wallingford, Connecticut 06492
                    (Address of principal executive offices)

                         NOVAMETRIX MEDICAL SYSTEMS INC.
                          1997 LONG TERM INCENTIVE PLAN

                         NOVAMETRIX MEDICAL SYSTEMS INC.
                             EMPLOYEE WARRANTS PLAN


                             WILLIAM J. LACOURCIERE
                      President and Chief Executive Officer
                         Novametrix Medical Systems Inc.
                               5 Technology Drive
                         Wallingford, Connecticut 06492
                                 (203) 265-7701
                      (Name, address and telephone number,
                   including area code, of agent for service)

                                    Copy to:
                              JOHN J. BUTLER, Esq.
                                 Haythe & Curley
                                 237 Park Avenue
                            New York, New York 10017

        Approximate date of commencement of proposed sale to the public:
   As soon as practicable after the Registration Statement becomes effective.

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
==============================================================================================
                                      Proposed maximum    Proposed maximum
Title of securities    Amount to be    offering price    aggregate offering      Amount of
 to be registered       registered        per share*           price*         registration fee
 ----------------       ----------        ----------           ------         ----------------
<S>                   <C>             <C>                <C>                  <C>      
Common Stock          550,000 shares        $7.00            $3,850,000          $1,135.75
($.01 par value)
==============================================================================================
</TABLE>

*Estimated solely for purposes of calculating the registration fee on the basis
of the average of the high and low prices of the Common Stock on July 17, 1998
as reported on the NASDAQ Stock Market.


                               Page 1 of 28 Pages
<PAGE>   2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


Item 3. Incorporation of Documents by Reference.

                  The Company hereby states that (i) the documents listed in (a)
through (b) below are incorporated by reference in this Registration Statement
and (ii) all documents subsequently filed by the Company pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as amended,
prior to the filing of a post-effective amendment which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference in this
Registration Statement and to be a part hereof from the date of filing of such
documents.

                  (a) The Company's Annual Report on Form 10-K for the year
ended May 3, 1998.

                  (b) The description of the Company's Common Stock contained in
the Company's registration statement on Form 10 dated July 24, 1979.

Item 4. Description of Securities.

                  Not applicable.

Item 5. Interests of Named Experts and Counsel.

                  The Company's counsel in connection with the offering is
Haythe & Curley. Thomas M. Haythe, a partner in the law firm of Haythe & Curley,
is a director of the Company. As of July 1, 1998, Mr. Haythe held 116,540 shares
of the Company's Common Stock and currently exercisable warrants to purchase
8,333 shares of Common Stock of the Company. In addition, other partners in
Haythe & Curley hold an aggregate of 141,562 shares of Common Stock of the
Company.

Item 6. Indemnification of Directors and Officers.

                  Section 145 of the General Corporation Law of the State of
Delaware Law ("Delaware Law") permits a corporation to indemnify its officers
and directors against liability in derivative and non-derivative actions if the
officer or director acted in good faith and in a manner he reasonably believed
to be in the best interests of the corporation and, in a criminal proceeding, if
he had no reasonable cause to believe that his conduct was unlawful. In
addition, Section 145 provides that an officer or director may be indemnified
against liability for action taken while serving another entity at the request
of the corporation so long as his actions were not opposed to the best interests
of the corporation.

                  Article Seventh of the Company's Certificate of Incorporation
provides that the Company shall indemnify and hold harmless any director or
officer of the Company from and against any and all expenses and liabilities
that may be imposed upon or incurred by him in connection with, or as a result
of, any proceeding in which he may become involved, as a party or otherwise, by
reason of the fact that he is or was such a director or officer of the Company,
whether or not he continues to be such at the time such expenses and liabilities
shall have been imposed or incurred, under certain prescribed circumstances and
subject to the laws of the State of Delaware.


                                      II-1
<PAGE>   3
                  The Company's Certificate of Incorporation contains a
provision which eliminates the personal liability of a director of the Company
to the Company or to any of its stockholders for monetary damages for a breach
of his fiduciary duty as a director, except in the case where the director
breached his duty of loyalty, failed to act in good faith, engaged in
intentional misconduct or knowingly violated a law, authorized the payment of a
dividend or approved a stock repurchase in violation of Delaware corporate law,
or obtained an improper personal benefit.


Item 7. Exemption from Registration Claimed.

                  Not applicable.

Item 8. Exhibits.

                  The Exhibits required to be filed as part of this Registration
Statement are listed in the attached Index to Exhibits.

Item 9. Undertakings.

                  The undersigned Registrant hereby undertakes, except as
otherwise specifically provided in the rules of the Securities and Exchange
Commission promulgated under the Securities Act of 1933:

                  (1) To file, during any period in which offers or sales are
being made, a post-effective amendment to this Registration Statement:

                  (i) To include any prospectus required by section 10(a)(3) of
the Securities Act of 1933;

                  (ii) To reflect in the prospectus any facts or events arising
after the effective date of this Registration Statement (or the most recent
post-effective amendment hereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this Registration
Statement;

                  (iii) To include any material information with respect to the
plan of distribution not previously disclosed in this Registration Statement or
any material change to such information in this Registration Statement;

provided, however, that paragraphs (1)(i) and (1)(ii) do not apply if this
Registration Statement is on Form S-3, Form S-8 or Form F-3, and the information
required to be included in a post-effective amendment by those paragraphs is
contained in periodic reports filed with or furnished to the Securities and
Exchange Commission by the Registrant pursuant to section 13 or 15(d) of the
Securities Exchange Act of 1934 that are incorporated by reference in this
Registration Statement;

                  (2) That, for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof; and

                  (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

                  The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act of 1933, each
filing of the Registrant's annual report pursuant to section 13(a) or section
15(d) of the Securities Exchange Act of 1934 that is incorporated by reference
in this Registration Statement shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.


                                      II-2
<PAGE>   4
                  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Act and will
be governed by the final adjudication of such issue.


                                      II-3
<PAGE>   5
                                POWER OF ATTORNEY

                  The Registrant and each person whose signature appears below
hereby appoints William J. Lacourciere and Jeffery A. Baird as attorneys-in-fact
with full power of substitution, severally, to execute in the name and on behalf
of the Registrant and each such person, individually and in each capacity stated
below, one or more post-effective amendments to this Registration Statement as
the attorney-in-fact acting in the premises deems appropriate and to file any
such amendment to this Registration Statement with the Securities and Exchange
Commission.

                                       SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933,
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 Wallingford and State of Connecticut on the 24th
day of July, 1998.

                                       NOVAMETRIX MEDICAL SYSTEMS INC.



                                       By /s/ William J. Lacourciere
                                          --------------------------------------
                                          William J. Lacourciere
                                          Chairman of the Board, President,
                                          Chief Executive Officer and Director


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


Signature                      Title                                   Date
---------                      -----                                   ----

/s/ William J. Lacourciere     Chairman of the Board,              July 24, 1998
William J. Lacourciere         President, Chief
                               Executive Officer
                               and Director


/s/ Jeffery A. Baird           Chief Financial Officer and         July 24, 1998
Jeffery A. Baird               Principal Accounting Officer



/s/Paul A. Cote                Director                            July 24, 1998
Paul A. Cote



/s/Thomas M. Haythe            Director                            July 24, 1998
Thomas M. Haythe


                                      II-4
<PAGE>   6
Signature                      Title                                   Date
---------                      -----                                   ----

/s/ John P. Mahoney            Director                            July 24, 1998
John P. Mahoney



/s/ Photios T. Paulson         Director                            July 24, 1998
Photios T. Paulson



/s/ Steven J. Shulman          Director                            July 24, 1998
Steven J. Shulman



/s/ Vartan Ghugasian           Director                            July 24, 1998
Vartan Ghugasian


                                      II-5
<PAGE>   7
                               CONSENT OF COUNSEL


                  The consent of Haythe & Curley is contained in their opinion
filed as Exhibit 5 to this Registration Statement.


                                      II-6
<PAGE>   8
                         CONSENT OF INDEPENDENT AUDITORS


                  We consent to the incorporation by reference in the
Registration Statement (Form S-8) pertaining to the Novametrix Medical Systems
Inc. 1997 Long Term Incentive Plan and the Novametrix Medical Systems Inc.
Employee Warrants Plan of our report dated June 24, 1998, with respect to the
consolidated financial statements and schedules of Novametrix Medical Systems
Inc. included in its Annual Report (Form 10-K) for the year ended May 3, 1998,
filed with the Securities and Exchange Commission.


                                       ERNST & YOUNG LLP

Hartford, Connecticut
July 21, 1998


                                      II-7
<PAGE>   9
                                INDEX TO EXHIBITS


Number                        Description of Exhibit                        Page
------                        ----------------------                        ----

4(i)        -  Novametrix Medical Systems Inc. 1997 Long Term                E-1
               Incentive Plan

4(ii)       -  Form of Warrant Certificate for Novametrix Medical           E-14
               Systems Inc. Employee Warrants Plan

5           -  Opinion of Haythe & Curley                                   E-19

23(i)       -  Consent of Ernst & Young LLP, Independent Auditors (see       --
               "Consent of Independent Auditors" in the Registration
               Statement)

23(ii)      -  Consent of Haythe & Curley (contained in Exhibit 5)           --

24          -  Power of Attorney (see "Power of Attorney" in the             --
               Registration Statement)


                                      II-8
[{"type": "S-8", "sequence": "1", "description": "REGISTRATION STATEMENT ON FORM S-8", "secsgml_size_bytes": 16158}]
{"company-data": {"conformed-name": "NOVAMETRIX MEDICAL SYSTEMS INC", "cik": "0000310450", "assigned-sic": "3845", "irs-number": "060977422", "state-of-incorporation": "DE", "fiscal-year-end": "0429"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-59809", "film-number": "98671070"}, "business-address": {"street1": "1 BARNES INDUSTRIAL PARK RD", "city": "WALLINGFORD", "state": "CT", "zip": "06492", "phone": "203-265-77"}, "mail-address": {"street1": "1 BARNES INDUSTRIAL PARK ROAD", "city": "WALLINGFORD", "state": "CT", "zip": "06492"}}
1
      As filed with the Securities and Exchange Commission on July 24, 1998
                              Subject to amendment.
                                                           Registration No. 33-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

                         NOVAMETRIX MEDICAL SYSTEMS INC.
             (Exact name of registrant as specified in its charter)

            DELAWARE                                             06-0977422
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)

                               5 Technology Drive
                         Wallingford, Connecticut 06492
                    (Address of principal executive offices)

                         NOVAMETRIX MEDICAL SYSTEMS INC.
                          1997 LONG TERM INCENTIVE PLAN

                         NOVAMETRIX MEDICAL SYSTEMS INC.
                             EMPLOYEE WARRANTS PLAN

                             WILLIAM J. LACOURCIERE
                      President and Chief Executive Officer
                         Novametrix Medical Systems Inc.
                               5 Technology Drive
                         Wallingford, Connecticut 06492
                                 (203) 265-7701
                      (Name, address and telephone number,
                   including area code, of agent for service)

                                    Copy to:
                              JOHN J. BUTLER, Esq.
                                 Haythe & Curley
                                 237 Park Avenue
                            New York, New York 10017

        Approximate date of commencement of proposed sale to the public:
   As soon as practicable after the Registration Statement becomes effective.

                         CALCULATION OF REGISTRATION FEE
==============================================================================================
                                      Proposed maximum    Proposed maximum
Title of securities    Amount to be    offering price    aggregate offering      Amount of
 to be registered       registered        per share*           price*         registration fee
 ----------------       ----------        ----------           ------         ----------------
Common Stock          550,000 shares        $7.00            $3,850,000          $1,135.75
($.01 par value)
==============================================================================================
*Estimated solely for purposes of calculating the registration fee on the basis
of the average of the high and low prices of the Common Stock on July 17, 1998
as reported on the NASDAQ Stock Market.

                               Page 1 of 28 Pages
2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

                  The Company hereby states that (i) the documents listed in (a)
through (b) below are incorporated by reference in this Registration Statement
and (ii) all documents subsequently filed by the Company pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as amended,
prior to the filing of a post-effective amendment which indicates that all
securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference in this
Registration Statement and to be a part hereof from the date of filing of such
documents.

                  (a) The Company's Annual Report on Form 10-K for the year
ended May 3, 1998.

                  (b) The description of the Company's Common Stock contained in
the Company's registration statement on Form 10 dated July 24, 1979.

Item 4. Description of Securities.

                  Not applicable.

Item 5. Interests of Named Experts and Counsel.

                  The Company's counsel in connection with the offering is
Haythe & Curley. Thomas M. Haythe, a partner in the law firm of Haythe & Curley,
is a director of the Company. As of July 1, 1998, Mr. Haythe held 116,540 shares
of the Company's Common Stock and currently exercisable warrants to purchase
8,333 shares of Common Stock of the Company. In addition, other partners in
Haythe & Curley hold an aggregate of 141,562 shares of Common Stock of the
Company.

Item 6. Indemnification of Directors and Officers.

                  Section 145 of the General Corporation Law of the State of
Delaware Law ("Delaware Law") permits a corporation to indemnify its officers
and directors against liability in derivative and non-derivative actions if the
officer or director acted in good faith and in a manner he reasonably believed
to be in the best interests of the corporation and, in a criminal proceeding, if
he had no reasonable cause to believe that his conduct was unlawful. In
addition, Section 145 provides that an officer or director may be indemnified
against liability for action taken while serving another entity at the request
of the corporation so long as his actions were not opposed to the best interests
of the corporation.

                  Article Seventh of the Company's Certificate of Incorporation
provides that the Company shall indemnify and hold harmless any director or
officer of the Company from and against any and all expenses and liabilities
that may be imposed upon or incurred by him in connection with, or as a result
of, any proceeding in which he may become involved, as a party or otherwise, by
reason of the fact that he is or was such a director or officer of the Company,
whether or not he continues to be such at the time such expenses and liabilities
shall have been imposed or incurred, under certain prescribed circumstances and
subject to the laws of the State of Delaware.

                                      II-1
3
                  The Company's Certificate of Incorporation contains a
provision which eliminates the personal liability of a director of the Company
to the Company or to any of its stockholders for monetary damages for a breach
of his fiduciary duty as a director, except in the case where the director
breached his duty of loyalty, failed to act in good faith, engaged in
intentional misconduct or knowingly violated a law, authorized the payment of a
dividend or approved a stock repurchase in violation of Delaware corporate law,
or obtained an improper personal benefit.

Item 7. Exemption from Registration Claimed.

                  Not applicable.

Item 8. Exhibits.

                  The Exhibits required to be filed as part of this Registration
Statement are listed in the attached Index to Exhibits.

Item 9. Undertakings.

                  The undersigned Registrant hereby undertakes, except as
otherwise specifically provided in the rules of the Securities and Exchange
Commission promulgated under the Securities Act of 1933:

                  (1) To file, during any period in which offers or sales are
being made, a post-effective amendment to this Registration Statement:

                  (i) To include any prospectus required by section 10(a)(3) of
the Securities Act of 1933;

                  (ii) To reflect in the prospectus any facts or events arising
after the effective date of this Registration Statement (or the most recent
post-effective amendment hereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this Registration
Statement;

                  (iii) To include any material information with respect to the
plan of distribution not previously disclosed in this Registration Statement or
any material change to such information in this Registration Statement;

provided, however, that paragraphs (1)(i) and (1)(ii) do not apply if this
Registration Statement is on Form S-3, Form S-8 or Form F-3, and the information
required to be included in a post-effective amendment by those paragraphs is
contained in periodic reports filed with or furnished to the Securities and
Exchange Commission by the Registrant pursuant to section 13 or 15(d) of the
Securities Exchange Act of 1934 that are incorporated by reference in this
Registration Statement;

                  (2) That, for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof; and

                  (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

                  The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act of 1933, each
filing of the Registrant's annual report pursuant to section 13(a) or section
15(d) of the Securities Exchange Act of 1934 that is incorporated by reference
in this Registration Statement shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

                                      II-2
4
                  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Act and will
be governed by the final adjudication of such issue.

                                      II-3
5
                                POWER OF ATTORNEY

                  The Registrant and each person whose signature appears below
hereby appoints William J. Lacourciere and Jeffery A. Baird as attorneys-in-fact
with full power of substitution, severally, to execute in the name and on behalf
of the Registrant and each such person, individually and in each capacity stated
below, one or more post-effective amendments to this Registration Statement as
the attorney-in-fact acting in the premises deems appropriate and to file any
such amendment to this Registration Statement with the Securities and Exchange
Commission.

                                       SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933,
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 Wallingford and State of Connecticut on the 24th
day of July, 1998.

                                       NOVAMETRIX MEDICAL SYSTEMS INC.

                                       By /s/ William J. Lacourciere
                                          --------------------------------------
                                          William J. Lacourciere
                                          Chairman of the Board, President,
                                          Chief Executive Officer and Director

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

Signature                      Title                                   Date
---------                      -----                                   ----

/s/ William J. Lacourciere     Chairman of the Board,              July 24, 1998
William J. Lacourciere         President, Chief
                               Executive Officer
                               and Director

/s/ Jeffery A. Baird           Chief Financial Officer and         July 24, 1998
Jeffery A. Baird               Principal Accounting Officer

/s/Paul A. Cote                Director                            July 24, 1998
Paul A. Cote

/s/Thomas M. Haythe            Director                            July 24, 1998
Thomas M. Haythe

                                      II-4
6
Signature                      Title                                   Date
---------                      -----                                   ----

/s/ John P. Mahoney            Director                            July 24, 1998
John P. Mahoney

/s/ Photios T. Paulson         Director                            July 24, 1998
Photios T. Paulson

/s/ Steven J. Shulman          Director                            July 24, 1998
Steven J. Shulman

/s/ Vartan Ghugasian           Director                            July 24, 1998
Vartan Ghugasian

                                      II-5
7
                               CONSENT OF COUNSEL

                  The consent of Haythe & Curley is contained in their opinion
filed as Exhibit 5 to this Registration Statement.

                                      II-6
8
                         CONSENT OF INDEPENDENT AUDITORS

                  We consent to the incorporation by reference in the
Registration Statement (Form S-8) pertaining to the Novametrix Medical Systems
Inc. 1997 Long Term Incentive Plan and the Novametrix Medical Systems Inc.
Employee Warrants Plan of our report dated June 24, 1998, with respect to the
consolidated financial statements and schedules of Novametrix Medical Systems
Inc. included in its Annual Report (Form 10-K) for the year ended May 3, 1998,
filed with the Securities and Exchange Commission.

                                       ERNST & YOUNG LLP

Hartford, Connecticut
July 21, 1998

                                      II-7
9
                                INDEX TO EXHIBITS

Number                        Description of Exhibit                        Page
------                        ----------------------                        ----

4(i)        -  Novametrix Medical Systems Inc. 1997 Long Term                E-1
               Incentive Plan

4(ii)       -  Form of Warrant Certificate for Novametrix Medical           E-14
               Systems Inc. Employee Warrants Plan

5           -  Opinion of Haythe & Curley                                   E-19

23(i)       -  Consent of Ernst & Young LLP, Independent Auditors (see       --
               "Consent of Independent Auditors" in the Registration
               Statement)

23(ii)      -  Consent of Haythe & Curley (contained in Exhibit 5)           --

24          -  Power of Attorney (see "Power of Attorney" in the             --
               Registration Statement)

                                      II-8