[LETTERHEAD]

                        November 17, 1995


Mr. Richard M. Stern
Vice President, Marketing
Molecular Biosystems, Inc.
10030 Barnes Canyon Road
San Diego, California  92121

          Re:  Terms of Separation from MBI
               ----------------------------

Dear Rich:

     In accordance with our recent discussions, this letter ("Letter 
Agreement") will set forth the terms of our agreement regarding your 
voluntary departure from MBI.

     1.   DESCRIPTION.  Both parties shall regard your departure as a 
voluntary resignation to pursue personal goals and other opportunities.

     2.   TIMING.  You shall resign as an employee and officer of MBI 
effective as of December 2, 1995 ("Resignation Date").  Your resignation 
shall be in the form attached hereto.

     EFFECTIVE DATE.  This Letter Agreement and the Consultant Agreement (see 
Paragraph 3) shall become effective on the eighth day following your 
execution of both agreements, unless you have revoked acceptance during the 
seven days prior thereto.  (SEE ALSO Paragraph 15(b).) Regardless of when 
this takes place, the Agreements shall be deemed to have been in effect 
retroactive to December 2, 1995.  Neither agreement shall become effective 
unless both are executed by you and MBI.

     3.   CONSULTING.  Because you are a long-time employee of MBI, we would 
like to be able to avail ourselves of your expertise after your departure.  
Effective as of December 2, 1995, we shall enter into a one-year Consultant 
Agreement substantially in the form attached hereto. Its terms are 
incorporated herein by reference, and vice versa.

     4.   WELFARE BENEFITS.  Regular medical, dental, vision and life 
insurance will continue through December 31, 1995, accidental death and 
dismemberment insurance, and long-term disability coverage will continue 
through the Resignation Date and end thereafter.  In addition:





Mr. Richard M. Stern
November 17, 1995
Page 2


          (a)  Medical, dental, and vision insurance under MBI's policies for
     you and currently insured dependents will be extended through COBRA from
     January 1, 1996 through December 31, 1996 (or until the Consultant
     Agreement is earlier terminated) at MBI's expense.  Thereafter, you may
     elect to continue COBRA coverage at your expense for an additional six
     months.  (Maximum COBRA coverage is 18 months.)

          (b)  You will be provided the information needed to request the option
     of converting the group life insurance coverage to an individual policy
     through NorthWestern National Life ("NWNL").  You will work directly with
     NWNL should you elect this option.  You would need to exercise this option
     within 31 days of the benefits termination date, December 31, 1995.

          (c)  You will be provided the information needed to request the option
     of converting the LTD insurance coverage to an individual policy through
     UNUM.  You should work directly with UNUM should you elect this option.
     You would need to exercise this option within 31 days of your resignation
     date, December 2, 1995.

          (d)  Depending on the size of your 401(k) plan account, you may either
     elect to remain in the plan with no further deposits (balance greater than
     $3500), or elect a distribution of your funds (balance less than $3500).
     You will notify MBI within 30 days of the Resignation Date as to how and to
     whom your funds should be distributed. Representatives of Human Resources
     will provide additional details and information regarding tax consequences
     of your various options.

          (e)  If you are a participant in the health care reimbursement plan,
     you will have until the end of 1995 to request reimbursement for charges
     incurred through the Resignation Date.  Any such request should be made
     directly to UNUM.

          (f)  You will be paid for all earned and unused vacation hours.  You
     will not accrue any additional vacation during the period of your
     Consultant Agreement.

Representatives of Human Resources will be available to explain details of 
these items. 




Mr. Richard M. Stern
November 17, 1995
Page 3


     5.   STOCK OPTIONS.

          (a)  CURRENT OPTIONS.  You have been granted stock options as
     described in the attached schedule.  As of December 2, MBI will accelerate
     the vesting of all unvested options.  MBI will also extend the period of
     exercisability of those options to the maximum period available under our
     plans.  (That is, the lapse dates in the charts, which are already at the
     maximum, will not be reduced on account of your ceasing to be an employee.)

          (b)  NEW OPTIONS.  MBI will grant you 10,000 additional options which
     will vest in full at an exercise price equal to the closing price of MBI
     common stock on December 1, 1995.  The options will be exercisable until
     December 1, 2005.

Until May 31, 1996 ("Reporting Period"), you will be under the same 
constraints imposed by MBI and securities laws on MBI vice presidents 
regarding the exercise of options and the purchase and sale of MBI shares.  
During the Reporting Period, you shall notify us of your intentions in this 
regard (including option exercises) and shall execute such forms, if any, as 
MBI and the U.S. securities laws require.  If you wish, you may use the 
services of Ruth Coolong (or her successor or designee) to assist you in 
exercising your options and selling your shares (if that is how you choose to 
proceed) during the Reporting Period.  You acknowledge that taxes and 
commissions will be withheld from any profit you make on the sale of the 
stock following exercise and sale during the Reporting Period.  During the 
Reporting Period, you will be notified monthly, along with other MBI Section 
16(b) reporting persons, as to the current trading status of MBI stock (i.e., 
"green light," "yellow light," or "red light").  At no time -- presently, or 
at any future time, during or after the Reporting Period -- may you trade on 
inside MBI information.

     MBI shall also pay you the $16,800 you borrowed to pay taxes upon 
exercise of your loan, grossed up for taxes, upon presentation of your loan 
documentation.

     6.   PLACEMENT.  MBI will provide you with six months' outplacement 
counseling and services through Lee Hecht Harrison.

     7.   COOPERATION;  NO RAIDING; NON-DISPARAGEMENT.  You shall cooperate 
with MBI in any and all governmental and/or third-party proceedings,





Mr. Richard M. Stern
November 17, 1995
Page 4


including but not limited to lawsuits and other disputes.  Following your 
resignation such cooperation shall be at MBI's expense (except that MBI 
cannot pay for the content of sworn testimony).  You shall keep MBI advised 
of contacts by governmental agencies and third parties, and shall reasonably 
cooperate with MBI in handling any response.  At your request, MBI shall 
provide counsel to you, if the parties deem counsel necessary or desirable, 
in any such proceeding.  You shall not voluntarily cooperate with, testify 
for, or otherwise assist parties adverse to MBI in a dispute, although you 
may respond to compulsory process (i.e., a valid subpoena).  

     For a period of one year following the Termination Date, you shall not 
contact persons employed by MBI at the time to recruit them for your business 
or any business by which you are employed or with which you are affiliated, 
or otherwise encourage them to leave MBI.

     You shall not materially disparage MBI, and MBI shall not materially 
disparage you, to any third parties.

     8.   CONTACTS BY POTENTIAL EMPLOYERS.  Potential employers contacting 
MBI will be told only that your resignation was voluntary; your title; your 
dates of employment; and your final salary.  MBI will provide you with a 
positive letter of reference.  The letter will be agreed upon between you and 
me.

     9.   CONFIDENTIALITY.  You will not remove any MBI information, 
documents, or other property from its premises, and you will return any MBI 
information currently in your possession or control off MBI's premises.  In 
addition:  

          (a)  You acknowledge that in the course of your employment with MBI
     you have had and will have access to and familiarity with information of
     substantial value to MBI which is not old or generally known to the public
     and which gives MBI an advantage over its competitors who do not know or
     use it, including but not limited to strategies, business plans, research,
     formulas and formulations, techniques, designs, drawings, processes,
     inventions, developments, equipment, prototypes, sales and customer
     information, and financial information, relating to the business, products,
     and practices of MBI (hereinafter referred to as "Confidential
     Information").  You agree at all times following your resignation to regard
     and preserve as confidential such Confidential Information, and to refrain
     from publishing or disclosing any part of such Confidential Infor-





Mr. Richard M. Stern
November 17, 1995
Page 5


     mation and from using it except on behalf of MBI.  You further agree at all
     times to refrain from any other acts or omissions that would reduce the
     value of such Confidential Information to MBI and to take all reasonably
     necessary and desirable precautions to prevent such Confidential
     Information from being disseminated to any third parties.

          (b)  You acknowledge that a breach of the terms of this paragraph
     would threaten MBI with immediate and irreparable harm not readily
     compensable in money damages, and that MBI would be entitled to injunctive
     and declaratory relief to stop or prevent any such breach.

Nothing in this paragraph shall be construed to prevent you from using or 
disclosing your general knowledge of the imaging industry (as opposed to 
MBI-specific information) acquired at any time prior to or during the course 
of your employment.

    10.  EMPLOYMENT BY COMPETITORS.  This Letter Agreement does not limit 
your ability to work for competitors of MBI, PROVIDED THAT for a period of 
one year from the Resignation Date, reasonably in advance of accepting any 
employment with any company, individual, or other entity engaged or planning 
to engage in the development, manufacture, or marketing of ultrasound 
contrast agents ("Competitor"), you shall notify the President or Chief 
Executive Officer of MBI.  Prior to accepting any such employment, or 
promptly following your engagement in any consulting relationship with a 
Competitor, you shall give MBI the opportunity to discuss your plans with you 
in order to explore any possible problems or conflicts. While MBI shall not 
disparage you or attempt to dissuade any Competitor from employing or 
engaging you, you acknowledge that MBI may contact such Competitor informing 
it truthfully of your confidentiality obligations to MBI.  MBI shall have no 
liability to you in the event of a decision by a Competitor not to employ or 
engage you following such contact by MBI.  Failure to provide this notice to 
MBI during this period shall be deemed a material breach of this Agreement.

     You remain bound by your confidentiality obligations even if you work 
for a Competitor.

    11.  LOAN.  You executed a Note in favor of MBI dated December 31, 1993, 
in the principal amount of $218,766.03.  As amended by an Amendment dated 
December 31, 1994, it is due and payable on January 31, 1996.   The loan is 
secured by 15,000 shares of MBI stock (certificate number MB 1698; "the





Mr. Richard M. Stern
November 17, 1995
Page 6

Subject Shares") purchased with the loan proceeds as a result of the exercise 
of a stock option.  With interest, the indebtedness evidenced by the Note has 
risen to approximately $243,000.  The indebtedness evidenced by the Note, as 
amended, shall be retired as follows:  MBI shall purchase the Subject Shares 
from you effective December 2, 1995, at the higher of (1) the closing price 
of MBI common stock on the New York Stock Exchange as of December 1, 1995, or 
(2) the average closing price of MBI common stock on the New York Stock 
Exchange on the twenty trading days prior to December 1, 1995.  The purchase 
proceeds shall be used to reduce the Note.  (Cash will not change hands; this 
will be handled by bookkeeping entries.)  MBI shall forgive the remaining 
indebtedness and the Note shall be canceled.

     EXAMPLE (if 11-8-95 were the effective date): 

          Indebtedness:            $243,000

          Purchase price:          $7.70 per share

          Times 15,000 shares      ($115,500)

          Remaining debt           $127,500

     MBI will forgive the remaining indebtedness of $127,500.

     MBI believes, BUT DOES NOT WARRANT, REPRESENT, OR PROMISE, (1) that the 
debt forgiveness will not result in current taxable income to you, but will 
instead serve to reduce your basis in the shares for purposes of your tax 
accounting, and (2) under the circumstances of your option exercise and the 
forgiveness, this transaction will leave you with a tax loss which you may 
use to offset certain other income in the future.  MBI will not include the 
forgiveness on your W-2. MBI STRONGLY RECOMMENDS THAT YOU SECURE COMPETENT 
TAX ADVICE WITH RESPECT TO THE ACCOUNTING AND TAX TREATMENT OF THE DESCRIBED 
TRANSACTION PRIOR TO EXECUTING THIS LETTER AGREEMENT.  Additional information 
with respect to your loan:

          Option price:                      $12.50
          Market price on exercise date      $17.375
          Taxes advanced and added to loan   $20,627 (approx.)
          Accrued interest to 11-8-95        $34,697 (approx.)





Mr. Richard M. Stern
November 17, 1995
Page 7


          Average per share price from       $7.70 (purposes of example
          10-10-95 to 11-7-95                      only; actual value may
                                                   be lower or higher,
                                                   depending on prices
                                                   on and prior to
                                                   December 1, 1995.

Jerry Wills will explain the basis for MBI's belief to you and/or your 
professional advisors, if you wish.

    12.  RELEASE.  In consideration for the payments, options, loan 
forgiveness, and other consideration described in this Letter Agreement and 
the Consultant Agreement, you hereby unconditionally, irrevocably, and 
absolutely release and discharge MBI, its employees, officers, directors, 
agents, stockholders, independent contractors, attorneys, consultants, 
predecessors, successors and assigns from any and all claims related in any 
way to any acts, transactions, or occurrences between you and MBI to date, 
including but not limited to all losses, liabilities, claims, charges, 
demands and causes of action, known or unknown, suspected or unsuspected, 
arising directly or indirectly out of, or in any way connected with, your 
employment with or resignation from MBI.  This includes, but is not limited 
to, any claim of employment discrimination arising under federal, state or 
local law, including the Age Discrimination in Employment Act of 1967, as 
amended, the Americans with Disabilities Act, the California Fair Employment 
and Housing Act, any other statutory cause of action, and any tort or 
contract claims.

     WAIVER OF ADDITIONAL CLAIMS.  Section 1542 of the Civil Code of the 
State of California provides as follows:

     A general release does not extend to claims which the creditor does
     not know or suspect to exist in his favor at the time of executing the
     release, which if known by him must have materially affected his settlement
     with the debtor.

You waive and relinquish any right or benefit which you may have under this 
section or any other provision of the statutory or nonstatutory law or any 
other jurisdiction to the full extent that you may lawfully waive all such 
rights and benefits.  In connection with such waiver and relinquishment, you 
acknowledge that you are aware that you, your attorneys or agents may 
hereafter discover





Mr. Richard M. Stern
November 17, 1995
Page 8


claims or facts in addition to or different from those which they now know or 
believe to exist, but that it is your intention thereby fully, finally, and 
forever to release all claims, disputes, and differences, known or unknown, 
suspected or unsuspected, which now exist, may exist, or have existed between 
the parties, their employees, agents, assigns, and other privies.  Unless 
this provision shall have been procured by fraud, the releases given herein 
shall be effective regardless of the discovery or existence of any such claim 
or fact.

    13.  CONSEQUENCES OF BREACH.  If you breach this Letter Agreement, MBI 
may terminate it, cease providing payments and benefits hereunder, cancel 
your stock options, and recover all payments and benefits already paid, in 
addition to any other remedies it may have.

    14.  OTHER MATTERS.  You will also receive materials prepared by Human 
Resources describing various rights and duties, including optional benefits, 
which will come into effect following your resignation.  You will also 
receive instruments as are customarily submitted to resigning employees.  You 
will cooperate fully in these separation meetings and execute or complete 
such instruments at the time of your resignation.

    15.  ACKNOWLEDGEMENTS.

          (a)  NO PRE-EXISTING OBLIGATION.  You acknowledge that but for the 
     entry by you and MBI into this Letter Agreement and the Consultant 
     Agreement, you are not entitled to the payments, stock options, loan 
     forgiveness, and other consideration provided for in these agreements 
     (with the exception of federal rights such as COBRA).

          (b)  Time for Review; Effective Date.  You acknowledge that you have
     been given 21 days to consider the terms of this Letter Agreement and the
     Consultant Agreement. In addition, both parties acknowledge that you may
     revoke your acceptance of this Letter Agreement within seven days following
     your signature (which may occur during the 21-day period).

          (c)  Advice of Counsel and Other Professional Advisors.  You
     acknowledge that you have been advised in writing to consult with an
     attorney and an accountant or tax advisor before entering into these
     agreements.  You acknowledge either that you have done so and received
     counseling to your satisfaction, or that you have declined to do





Mr. Richard M. Stern
November 17, 1995
Page 9


     so and voluntarily executed this Letter Agreement and the Consultant
     Agreement without fraud or undue influence.

    16.  PROHIBITION AGAINST ASSIGNMENT.  You shall not assign this Letter 
Agreement or any of the rights, interests and benefits hereunder.  However, 
you may provide for the assignment, gift, bequest, or transfer of such 
benefits under this Letter Agreement to your survivor(s), or to a trust for 
their benefit, on your death, or in the event that you suffer a major 
disability. 

    17.  ENTIRE AGREEMENT.  This Letter Agreement, along with the Consultant 
Agreement between the parties dated December 2, 1995, constitutes the entire 
Agreement between the parties hereto and contains all of the agreements 
between the parties with respect to its subject matter.  This Letter 
Agreement and the Consultant Agreement supersede any and all other 
agreements, either oral or in writing, between the parties hereto with 
respect to their subject matter, PROVIDED THAT Paragraphs 3 (Confidentiality) 
and 4-9 (relating to inventions made within a year of termination) of your 
Employment Agreement dated April 25, 1988, shall remain in effect.

    18.  BINDING EFFECT.  This Letter Agreement shall be binding upon and 
inure to the benefit of both parties and their respective heirs, legal 
representatives, executors, administrators, and successors.

    19.  GOVERNING LAW.  This Letter Agreement shall be subject to and 
governed by the laws of the State of California irrespective of the fact that 
you may become a resident of a different state.

    20.  AMENDMENT OF LETTER AGREEMENT. No change or modification of this 
Letter Agreement shall be valid unless the same be in writing and signed by 
both parties.  No waiver of any provision of this Letter Agreement shall be 
valid unless in writing and signed by the person or party to be charged.

    21.  SEVERABILITY.  If any portion or portions of this Letter Agreement 
shall be, for any reason, deemed to be invalid or unenforceable, the 
remaining portion or portions shall nevertheless be valid, enforceable and 
carried into effect, unless to do so would clearly violate the present legal 
and valid intention of the parties hereto.

    22.  HEADINGS.  The headings of this Letter Agreement are inserted for 
convenience only and are not to be considered in construction of the 
provisions




Mr. Richard M. Stern
November 17, 1995
Page 10


hereof.

    23.  WAIVER OF BREACH.  The waiver by  either of the parties hereto of 
any breach of any provision hereof shall not be construed to be a waiver of 
any succeeding breach of that provision or a waiver of any other provision of 
this Letter Agreement.

    24.  INDEMNIFICATION.  With respect to any claim against you arising out 
of your work for MBI as an officer or employee, or as a consultant under your 
Consultant Agreement, you shall have rights of indemnification against MBI 
under MBI's certificate of incorporation and bylaws equivalent to those of an 
MBI officer.

                            * * * *

     If you are in agreement with these items, please execute the duplicate 
originals of this Letter Agreement and Consultant Agreement and return them 
to Pam Alexandra, Jerry Wills, or Steve Lawson.

     Let me take this opportunity to thank you for your services to MBI over 
the past several years.  We all wish you every success in your future 
endeavors.

                              Sincerely,

                              /s/ B. Venkatadri

                              Bobba Venkatadri
                              President and Chief Operating Officer


AGREED TO BY:

  /s/ Richard M. Stern
- -------------------------------------------
  Richard M. Stern
Date: Dec 6, 1995
     --------------------------------------





                                       December 2, 1995




Mr. Bobba Venkatadri
President and Chief Operating Officer
Molecular Biosystems, Inc.
10030 Barnes Canyon Road
San Diego, California  92121

     Re:  Resignation

Dear Bobba:

     I resign as an employee and as Vice President, Marketing, of Molecular 
Biosystems, Inc., effective immediately.

                              Sincerely,

                              /s/ Richard M. Stern

                              Richard M. Stern
                              Vice President, Marketing