Objective To study the expression of muhidrug resistance( MDR1 ) ,and clinical significance of MDR1 gone expression in EOC. Methods Reverse transcription polymerase chain reaction was used to determine the expression of MDR1 in 27 cases of epithelial ovarian cancer,38 cases of benign tumor and 20 cases of normal ovarian tissue. The expression rate of MDR1 and the clinical significance was explored. Results The expression rate of MDR1 gone in malignant,benign tumor and normal tissue of ovary was74.1%, 15.7 % and 0 % respectively. The levd of MDR1 gone expression in EOC was obviously higher than that in benign tumor(P<0.01 ). The non-respond-era to combination chemotherapy exhibited higher ratio of MDR1 expression than the respondera( P<0.05 ). Conclu-sion The expression of MDR1 is higher in EOC than that in normal ovary tissue and benign tumor. The expression of MDR1 is closely related to the tumor response to chemotherapy.