Abstract: The function of MNNG on the proliferation of cultured cells from adult Schistosome were cultured in medium RPMI_1640 containing 20% calf serum and a moderate amount of antibiotics.Five days later,they were treated by MNNG with concentrations of 0,1,2,3,4,6 and 9μg/ml for 0,24,36 and 48 hours,respectively.Afterwards they were moved into the original medium.Three weeks later,the rate of calf serum in the medium was adjusted into to 5%.The proliferation and growth of the treated cells were observed by microscope everyday.Most of the cells treated by MMNG with concentrations of 6 and 9μg/ml fell off from the wall of culture flasks after 3 dyas,and the remained cells cultured in the medium containing 5% calf serum declined gradually.All the cells treated by MNNG of 1,2,3,and 4μg/ml grew well in the medium.The volume of the cells was larger and more cells in division were observed in the first groups than those in the control.especially in the cells treated by MNNG of the concentration of 3μg/ml for 48 hours.MNNG with the moderate concentration can induce the proliferation and division of cultured cells from adult Schistosoma japonicum.