Despite high primary response rates with cisplatin-based combination chemotherapy, the overall survival rate for advanced ovarian cancer remains unsatisfactory. This prompted us to design a new systematic approach using a combination chemotherapy consisting of cisplatin, doxorubicin, and cyclophosphamide (PAC), namely, cyclic PAC chemotherapy. This is a 3-step chemotherapy with 3 courses of the PAC regimen in each step. It was administered for 18 months to patients with clinical Stage Ic-IV ovarian cancer, after cytoreductive surgery. In the present study, the cyclic PAC, brief PAC, and FAM (5-Fu, an alkylating agent, and mitomycin C) groups included 27 cases, 34 cases, and 38 cases, respectively. Treatment of Stage Ic-IV disease by cyclic PAC improved the outcome (57% estimated 5-year survival rate) compared to brief-PAC and FAM (20% and 32%, respectively). The outcome for patients with Stage III or IV ovarian cancer was also superior for the cyclic-PAC group compared to the brief-PAC and FAM groups (cyclic-PAC 44%, brief-PAC 9%, and FAM 0% estimated 5-year survival rates). Cyclic PAC chemotherapy was thus found to be capable of dramatically improving the long-term survival rate of ovarian cancer patients.