Five patients who developed leukemia after chemotherapy for ovarian cancer are reported. All patients received the platinum analogue cyclophosphamide, a known leukemogen. In two patients, the leukemia was diagnosed after second-line chemotherapy with carboplatin, cyclophosphamide, and pirarubicin hydrochloride following intraperitoneal chemotherapy that included etoposide. Four patients had acute nonlymphocytic leukemia. The latency period was 16–63 months. Chromosomal analysis was performed in four patients and partial deletion of the long arm of chromosome 6, partial deletion of the long arm of chromosome 7, and multiple abnormalities were observed in all four. Remission of leukemia was not experienced; three patients died of leukemia and two died of primary ovarian cancer.