An early Phase II study of CTP-11, a new derivative of Camptothecin, in gynecologic cancers was carried out by a cooperative study group of 9 institutions. Forty-six patients were enrolled, and there were 14 cases of ovarian cancers, 7 of cervical cancer, 6 of uterine body cancers and 1 of endometrial stromal sarcoma which satisfied study criteria. The response rate in ovarian cancers was 21.4%, and in cervical cancers 42.9%, among an overall rate of 21.4%. Three out of 6 patients with objective response had undergone previous chemotherapies including cisplatin, suggesting that CPT-11 was effective for patients with no response or refractory to these therapies. Leukopenia was a major adverse reaction with an incidence of 60.0% (grade 2 or more). Gastrointestinal symptoms such as nausea vomiting, anorexia and diarrhea were frequently observed (grade 2 or more; 13.3-43.3%). These were generally tolerable except in a few cases. Besides these reactions, alopecia was also observed (33.3%), but severe adverse reactions such as nephropathy were not. These results suggested that CPT-11 was effective against ovarian cancer and cervical cancer. The recommended dose regimen for a late phase II study is considered to be 100 mg/m2 once weekly and 150 mg/m2 once every 2 weeks.