Objective To elucidate the mechanism of prevention of postoperative tissues from adhesion by chitosan by stadying the effect of chitosan on indncing apoptosis of fibroblasts.Methods The cultured fibroblasts were treated for 48 hours with 0,0.01,0.1,1,10mg/ml chitosan,respectively.Then cell proliferation was detected by MTT assay and the cell apoptosis by flow cytometry.Results When the concentrations of chitosan were 0.01,0.1,1,and 10mg/ml,the optical density(A)values of the fibroblasts were 0.377?0.047,0.324?0.030,0.271?0.035 and 0.224?0.037,respectively,which were significantly lower than that of control group(0.561?0.044,P