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

FORM 4
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16.
    Form 4 or Form 5 obligations may continue.
1. Name and Address of Reporting Person(s)
   Dittrich, Howard
   10030 Barnes Canyon Blvd.


   San Diego, CA  92121
2. Issuer Name and Ticker or Trading Symbol
   Molecular Biosystems, Inc. (MB)
3. I.R.S. Identification Number of Reporting Person, if an entity (Voluntary)

4. Statement for Month/Year
   05/00
5. If Amendment, Date of Original (Month/Year)
   06/09/00
6. Relationship of Reporting Person(s) to Issuer (Check all applicable)
   [ ] Director                   [ ] 10% Owner
   [X] Officer (give title below) [ ] Other (specify below)
   Vice President, Research,
   Medical, & Regulatory Affairs
7. Individual or Joint/Group Filing (Check Applicable Line)
   [X] Form filed by One Reporting Person
   [ ] Form filed by More than One Reporting Person



Table I   Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
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1)Title of Security                           2)Trans-    3.Trans- 4.Securities Acquired(A)      5)Amount of    6)  7)Nature of
                                              action      action   or Disposed of (D)            Securities         Indirect
                                              Date        Code                   A               Beneficially   D   Beneficial
                                              (Month/                            or              Owned at       or  Ownership
                                              Day/Year)   Code V   Amount        D  Price        End of Month   I
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                           
Common Stock                                  05/09/00    J        19,101 (1)    D               41,373         D  Direct


Table II (PART 1)  Derivative Securities Acquired, Disposed of, or Beneficially Owned  (Columns 1 through 6)
- ------------------------------------------------------------------------------------------------------------------------------------
1)Title of Derivative          2)Conversion    3)Trans-       4)Trans-  5)Number of Derivative            6)Date Exercisable and
Security                       or Exercise     action         action    Securities Acquired (A)           Expiration Date
                               Price of        Date           Code      or Disposed of (D)
                               Derivative
                               Security                       Code  V   A                D                Exercisable  Expiration
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  
Incentive Stock Option (right  $0.7188         05/24/00       A         125,000 (2)                       05/24/01     05/24/10
to buy)


Table II (PART 2)  Derivative Securities Acquired, Disposed of, or Beneficially Owned  (Columns 1,3 and 7 through 11)
- ------------------------------------------------------------------------------------------------------------------------------------
1)Title of Derivative          3)Trans-  7)Title and Amount                           8)Price     9)Number of   10) 11)Nature of
Security                       action    of Underlying                                of Deri-    Derivative        Indirect
                               Date      Securities                                   vative      Securities    D   Beneficial
                                                                        Amount or     Security    Beneficially  or  Ownership
                                                                        Number of                 Owned at      I
                  -                      Title                          Shares                    End of Month
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                               
Incentive Stock Option (right  05/24/00  Common Stock                   125,000                   125,000       D   Direct
to buy)


Explanation of Responses:

(1)
Cancellation of shares in satisfaction of tax liability.
(2)
Option grants vest 25% per year over four years.



SIGNATURE OF REPORTING PERSON
/S/ By: Kevin Helmbacher
    For: Howard Dittrich
DATE