OBJECTIVE: To investigate whether the fermentation products of Omphalia lapidescens Schroet strain contain Leiwan proteinase with molecular weight and parasiticide effect on cysticercus cellulosae in vitro both similar to these of natural Leiwan. METHODS: We examined the fermentation products of Omphalia lapidescens Schroet strain, and tested the parasiticide effect on cysticercus cellulosae in vitro, in comparison with the natural Leiwan proteinase RESULTS: In the Leiwan proteinase extracted from the fermentation products of Omphalia Lapidescens Schroet strain, the molecular weight was 16 800, PI 4.4,and amino terminal valine. It had proteolysis activity and parasiticide effect on cysticercus cellulosae in vitro .CONCLUSION: There were no remarkable differences between the Leiwan proteinase obtained by the method of Omphalia Lapidescens Schroet strain fermenting, and the natural Leiwan proteinase.