The development and implementation of a concurrent circuit simulation program, CONCISE, for MOS circuits, which is targeted for multicomputers (that is, message-passing, concurrent computers), is described. The objective is to design a program that uses hundreds of processing nodes efficiently. Implementation issues which are of importance for the performance on a concurrent computer are discussed. The waveform relaxation method with full-window techniques and Jacobi iterations is used because of its simple scheduler and limited demands on the message-passing network of the multicomputer. To speed up convergence, time windows are placed at transitions in the input waveforms, and dynamic window splitting at the nonconvergence time point is used. Results of experiments performed on a 192-node multicomputer showing that CONCISE can efficiently exploit hundreds of nodes are presented. For large and medium-size problems the speedup is almost two orders of magnitude. It is shown that CONCISE can efficiently handle very large problems with 12000 circuit nodes.>