Between June 1977 and December 1979, 72 evaluable patients with childhood non-T-cell acute lymphoblastic leukemia were induced into complete remission using vincristine, prednisone, and doxorubicin. All received asparaginase consolidation and central nervous system prophylaxis with cranial irradiation and intrathecal methotrexate. All patients then received prolonged intensification with vincristine, prednisone, and doxorubicin, and half of them were randomized to receive weekly high-dose asparaginase. Continuation therapy was with vincristine, prednisone, methotrexate, and 6-mercaptopurine. After a median follow-up of 57 months, there were four remission deaths and 25 relapses. Central nervous system relapse was the first event in 4% of patients. There were fewer treatment failures in the asparaginase-treated group [2-sided, p = 0.04 (0.07 controlling for standard and high-risk groups)]. Asparaginase toxicity occurred in six patients (8%) and was self-limited, but it precluded further use of the drug in those patients. The major toxicity of this treatment program was drug-induced cardiomyopathy which occurred in 10 patients (14%) and was fatal in three of them. In summary, we conclude that the intensive use of high-dose asparaginase has an important role in the treatment of children with acute lymphoblastic leukemia. The morbidity of multiple doses of doxorubicin outweighed its antileukemic advantage in standard-risk patients.