A phase I/II study of bisantrene using a 3-week schedule was undertaken in 171 children with refractory leukemias and solid tumors. The doses ranged from 190 to 430 mg/m2. The maximum tolerated dose for children with solid tumors and acute leukemias was 280 mg/m2 and 360 mg/m2 every 3 weeks, respectively. The dose limiting toxicities were hepatic and hematologic. One patient with ALL achieved a complete remission and partial responses were observed in three patients with soft-tissue sarcomas. The data indicate that bisantrene, at the doses and schedule used in this study, has limited antitumor activity in pretreated children with cancer.