AbstractThis article analyzes a new technique for improving the efficiency of parallel fault simulation called Multiple Number of Faults per Pass. This technique partitions the total fault set into groups, taking care to avoid fictitious faults and fault masking. All the faults in one group are then inserted at the same time for one pass of a fault simulator. It was found from experiments on some sample circuits that with this method an efficiency improvement varying from 15% to 50% could be achieved over conventional parallel simulation.