Abstract: Objective To detect the expression of multidrug resistance gene (MDR1) in the epithelial ovarian carcinoma, and investigate its role in drug resistance. Methods The expression of MDR1 in 40 cases of ovarian carcinoma, 20 cases of benign ovarian tumor and 20 cases of normal control were determined by RT-PCR technique. The relations between MDR1 expression and the clinical-pathological characteristics as well as chemotherapeutic response were discussed. Results The positive expression rate of MDR1 in ovarian carcinoma was significantly higher than that in benign tumors and normal tissues, and a significant relationship was shown between its expression and pathologic differentiation, P<0.05. The MDR1 positive expression rate in cases received chemotherapy before surgery were significantly higher than in cases who didn't, P<0.05. The response rate in the MDR1 negative group was higher than that in the positive group (70.6% vs 43.5%), P<0.05. The predictive value of negative MDR1 staining for objective response was 70.6%. Conclusion These data suggested that MDR1 may play an important role in the acquired multidrug resistance of ovarian carcinoma. Determination of MDR1 expression may be useful for working out chemotherapy plan and predicting chemotherapeutic response of ovarian carcinoma patients.