OBJECTIVE To evaluate the role of combination chemotherapy and the optimal cycles of treatment in improving the prognosis of ovarian endodermal sinus tumor, and to study the relationship between the type of surgical management and the outcome of the disease. METHODS Sixty-three patients with ovarian endodermal sinus tumor were divided into 3 groups according to the postoperative chemotherapy they had received. Group 1 (37 patients) patients were treated with at least 6 cycles of VAC (vincristine, actinomycin-D and cytoxan) or 4 cycles of PVB (cysplatin, vincristine and bleomycin). Group 2 (17 patients) patients were treated with VAC in less than 6 cycles or PVB in less than 4 cycles. Group 3 (9 patients) patients received no VAC or PVB but some other drugs like TSPA, 5FU, MTX and cytoxan in various combinations. The sustained remission rates and survivals were compared among these 3 groups. For patients with full courses of treatment with VAC or PVB (Group 1), different types of surgical management were studied about their relationship with the outcome of the disease. RESULTS The persistent remission rates are 81.8%, 23.5% and 11.8% for group 1, group 2 and group 3 patients respectively (P < 0.001). The survival curve of group 1 is very much different from that of group 2 and group 3 patients. With full courses of chemotherapy with VAC or PVB, it appears that the different types of surgical managements (unilateral vs bilateral adenectomy; with vs without systemic lymphadenectomy; residual tumor < 2 cm vs > 2 cm) did not show definite relationship with the outcome of the disease. CONCLUSIONS Combination chemotherapy with VAC or PVB dramatically improved the prognosis of ovarian endodermal sinus tumor but it should be emphasized that the favorable results could be obtained only when the treatment is given on time and in optimal cycles. Although ovarian endodermal sinus tumor is chemosensitive, appropriate surgical treatment is still important, however, the surgical techniques need some further studies.