Objectives：To investigate the pathological and clinical effect of preoperative arterial infusion chemotherapy on breast cancers.Methods:Twenty patients with breast carcinoma received regional arterial angiography by Seldinger's procedure followed by arterial infusion chemotherapy.Sixteen patients who didn't undergo preoperative chemotherapy were selected as controls.All the operation specimens were analyzed by the same pathologist.Results:Histological analysis of the two groups revealed the following results:① cancer tissue necrosis increased in the arterial chemotherapy group;②karyopyknosis,karyorrhexis coagulation and necrosis of cytoplasm around the vascular vessels as well as interstitial edema were found in the tumor tissue,invasion of inflammatory cells,intimal proliferation thrombus and inflammation of vessels could also be seen.All the changes were much severe in the infusion chemotherapy group than in the controlled group;Conclusions:Histological changes are significant after preoperative arterial infusion chemotherapy for breast carcinoma.