Objectives. To estimate the antitumor activity of topotecan in patients with persistent or recurrent carcinosarcoma (malignant mixed mullerian tumors) of the uterus and to determine the nature and degree of toxicity of topotecan in this cohort of patients. Materials and methods. Eligible patients had measurable advanced or recurrent carcinosarcoma of the uterus. Topotecan at a target dose of 1.5 mg/m2 was administered IV daily for 5 days, every 3 weeks, until progression of disease or adverse affects prohibited further therapy. Results. Twenty-seven member institutions entered 51 patients. Of the patients entered, 48 were eligible. Patient characteristics included a median age of 65, with 33% having prior radiation and 92% having prior chemotherapy. Twenty-six patients (54% ) had a performance status (PS) of 0, 18 (38% ) had a PS of 1, and four (8% ) had a PS of 2. Patients received from 1 to 21 (with a median of 2) courses of treatment. The most frequently observed grade 4 toxicities were neutropenia seen in 35 (73% ) patients, leukopenia in 14 (29% ), and thrombocytopenia in 10 (21% ). Three (6% )- patients developed neutropenic sepsis and died shortly after their first treatment cycle. There were five (10% ) complete responses; 13 (27% ) patients maintained stable disease, 26 (54% ) experienced increasing disease, and reassessment did not occur in four (8% ). Conclusion. Topotecan at this dose and schedule does not appear to have major activity in patients with advanced or recurrent uterine carcinosarcoma previously treated with chemotherapy. Objectives. To estimate the antitumor activity of topotecan in patients with persistent or recurrent carcinosarcoma (malignant mixed mullerian tumors) of the uterus and to determine the nature and degree of toxicity of topotecan in this cohort of patients. Materials and methods. Eligible patients had measurable advanced or recurrent carcinosarcoma of the uterus. Topotecan at a target dose of 1.5 mg / m2 was administered IV daily for 5 days, every 3 weeks, until progression of disease or adverse affects prohibited further. Patients. Of the patients entered, 48 were eligible. Patient characteristics included a median age of 65, with 33% having prior radiation and 92% having prior chemotherapy. Twenty-six patients (54%) had a performance status (PS) of 0 The most frequently observed grade 4 toxicities were 18 (38%) had a PS of 1, and four (8%) had a PS of 2. Patients received from 1 to 21 (with a median of 2) courses of treatment. Three (6%) - patients developed neutropenic sepsis and died shortly after their first treatment cycle. There were five (73%) patients, leukopenia in 14 (29%), and thrombocytopenia in 10 Topotecan at this dose and schedule does not appear to (10%) complete responses; 13 (27%) patients maintained stable disease, 26 (54%) experienced increasing disease, and reassessment did not occur in four have major activity in patients with advanced or recurrent uterine carcinosarcoma previously treated with chemotherapy.