PMOTA, a parallel event-driven relaxation-based timing simulator of MOS circuits on distributed memory multiprocessors, is proposed. Two new schemes, one a static data distribution and dynamic event assignment, the other a global synchronism local asynchronism scheme, are derived to reduce the communication overhead and achieve high speedup ratio, high processor utilisation, and balanced load among processor elements. Implementation results show that parallel simulations on a distributed memory multiprocessor are feasible for large-scale circuit simulation.