1. Name and Address of Reporting Person
   MASSARO, GEORGE
   251 Ballardvale Street
   Wilmington, MA 01887
   USA
2. Date of Event Requiring Statement (Month/Day/Year)
   02/26/2003
3. IRS or Social Security Number of Reporting Person (Voluntary)
4. Issuer Name and Ticker or Trading Symbol
   Charles River Laboratories Int'l., Inc (CRL)
5. Relationship of Reporting Person(s) to Issuer (Check all applicable)
   (X) Director                   ( ) 10% Owner
   ( ) Officer (give title below) ( ) Other (specify below)
6. If Amendment, Date of Original (Month/Day/Year)
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 Beneficially Owned

+------------------------------------------+----------------------+----------------+-----------------------------------------------+
|1. Title of Security                      |2. Amount of          |3. Ownership    |4. Nature of Indirect Beneficial Ownership     |
|                                          |   Securities         |   Form:        |                                               |
|                                          |   Beneficially Owned |   Direct(D) or |                                               |
|                                          |                      |   Indirect(I)  |                                               |
+------------------------------------------+----------------------+----------------+-----------------------------------------------+
                                                                           





TABLE II -- Derivative Securities Beneficially Owned

+-----------------------+---------------------+---------------------------------+----------+-------------+-------------------------+
|1.Title of Derivative  |2.Date Exercisable   |3.Title and Amount of Securities |4.Conver- |5.Ownership  |6. Nature of Indirect    |
|  Security             |  and Expiration Date|  Underlying Derivative          | sion or  | Form of     |   Beneficial Ownership  |
|                       |  (Month/Day/Year)   |  Security                       | Exercise | Derivative  |                         |
|                       +----------+----------+-----------------------+---------+ Price of | Security:   |                         |
|                       | Date     | Expira-  |                       |Amount or| Deri-    | Direct(D) or|                         |
|                       | Exer-    | tion     |         Title         |Number of| vative   | Indirect(I) |                         |
|                       | cisable  | Date     |                       |Shares   | Security |             |                         |
+-----------------------+----------+----------+-----------------------+---------+----------+-------------+-------------------------+
                                                                                     

Explanation of Responses:


SIGNATURE OF REPORTING PERSON
/s/ GEORGE MASSARO

DATE
03/04/2003