Objective To explore the effect of chitosan on the prevention of postoperative peritoneal adhesion. Methods Forty-five Wistar rats were randomly assigned into group A(control group);group B and group C;2 ml of 1% lactic acid, 32% Dextran-70 or 2% Chitosan-lactic acid (CLA) was admitted on the region of serosal injury of intestine respectively during operation. The adhesive degree was observed and biopsy was taken on the 14th postoperative day. Results There were statistically significant differences among the degrees of adhesions between the three groups (P