OBJECTIVE： To evaluate the effect of CD44 on drug resistance of breast cancer patients. METHODS： 62 breast cancer patients were selected， and the expression of CD44 was detected by immunohistochemical method. Drug resistance was evaluated by WHO criteria， and the expression of CD44 in breast tissue was observed after observation. RESULTS： There were 48 patients sensitive to CD44 and 14 patients with drug resistance， with statistical significance（P＜0.05）. After chemotherapy， the expression of CD44 in caner tissue was higher than before chemotherapy， that of patients with drug resistance was higher than patients sensitive to CD44， with statistical significance （P＜0.01）. CONCLUSIONS： CD44 antigen is closely related to chemotherapy resistance of breast cancer， and high expression of CD44 can be used as an important indicator for breast cancer chemotherapy.