Abstract: Based on the timestamp, this paper presents a concurrency control algorithm for object oriented databases（OODB）, in which the traditional timestamp algorithm is expanded according to the data model of OODB. By using the semantics of the abstract data type （ADT）, the concurrency of accessing databases is enhanced with less overhead. The advantages of this algorithm are: （1） reducing extra storage spaces used for read and write timestamps by making use of the time information of object versions, and （2） eliminating the overhead of locking and deadlock prevention or deadlock detection in locking algorithm. Finally, the performance evaluation of our concurrency control algorithm is given compared with the locking algorithm in the ORION.