Bisantrene is an anthracene derivative which has demonstrated activity in acute myeloblastic leukemia (AML) and in lymphoma. The present study was designed to assess the reinduction rate and toxicity of bisantrene (250 mg/m2/d x 5) associated with aracytine (100 mg/m2 twice a day x 5) in refractory and relapsed acute childhood leukemia. Patients who relapsed after bone marrow transplantation were eligible. Twenty-six children were included. Diagnoses were as follows: 13 AML, 9 acute lymphoblastic leukemia (ALL), and 4 undifferentiated leukemia (AUL). All patients had been very highly pretreated, especially with anthracyclines, and most of them were of poor prognosis. The overall response rate was 46% with a 95% confidence interval ranging from 27-65%. According to diagnosis, complete remission (CR) rates are: AML: 5/13, ALL: 5/9, and AUL: 2/4. Four children died, three from infection and one from acute lysis syndrome. The major toxicity was infection with grade 3 and 4 episodes occurring in 42% of patients. No significant cardiac toxicity was noted. Hepatic and renal toxicity was noted. Hepatic and renal toxicity were limited and transient. Bisantrene in association with aracytine is effective in both AML and ALL of childhood. Bisantrene should be evaluated with a five-day schedule in other pediatric malignancies. In children with acute leukemia previously treated with high dose aracytine, new combination regimen is warranted.