A generalized stochastic simulation system has been developed to simulate experiments in cell cycle kinetics. The model to be simulated is described by the user according to his theoretical convictions, and the attributes of the experiment being simulated. In order to make the task of describing a model easy for the user a language is interfaced with the simulator. Special care has been taken in the design of this language to have it contain the terminology of the field of experimental biology, and to have it as flexible as possible to meet different areas of interests. The structure of the language has been kept as simple as possible in order to minimize the learning time. A program written in this language also reflects the assumptions as well as the logic in the model being described. The complete system has been implemented on an IBM 360/44 computer with 128K bytes of core memory. The language is described in detail, and the use of it is illustrated by simulating several experiments.