OBJECTIVE： To investigate the prevention and treatment effect of Xiaochaihu decoction on irinotecan （CPT-11）-induced bloodystool in model mice with delayed diarrhea. METHODS： 40 mice were randomly divided into normal control group （equal volume of normal saline）， model control group （equal volume of normal saline）， Xiaochaihu decoction group （1 500 mg/kg， calculated by crude drug） and loperamide group （positive control， 0.533 3 mg/kg）， ig， once a day， for 17 days. Except for normal control group， other groups were intraperitoneally injected CPT-11 to induce delayed diarrhea in 4th-10th day. Body mass changes， bloodystool rate of mice were determined， and pathological changes in large intestine and small intestine were observed. RESULTS： After 17 days of administration， compared with normal control group， the body mass in modeling groups was obviously declined （P＜0.05）， while body mass in Xiaochaihu decoction group was higher than model control group （P＜0.05）. In the 11th-17th day， bloodystool rate in Xiaochaihu decoction group and loperamide group were significantly lower than model control group （P＜0.01）， and bloodystool rate in Xiaochaihu decoction group was lower than loperamide group （P＜0.05）. Pathological results showed， obvious diffuse necrosis and inflammatory cell infiltration were observed in mucosal epithelial cells of large intestine and small intestine in model control group， and the intestinal mucosal tissue in administration groups tended to be normal. CONCLUSIONS： Xiaochaihu decoction can effectively reduce bloodystool rate， improve intestinal mucosa injury， and has prevention and treatment effect on CPT-11-induced bloodystool in mice， with superior effect to loperamide.