Adults (274) with acute leukemia (AML) were randomly assigned to one of three treatment regimens: vincristine, prednisone, cytarabine--(1) 100 mg/sq m/day with cyclophosphamide (COAP); (2) 100 mg/sq m/day with daunorubicin (DOAP); and 200 mg/sq m/day (OAP). Cytarabine was infused continuously for five days. Patients entering complete remission randomly received maintenance treatment with COAP or OAP. For 197 previously untreated AML patients given COAP, DOAP, or OAP, remission rates were 37%, 35%, and 43%, respectively; median lengths, 40, 45, and 90 weeks; median survival, 7, 11, and 8 weeks. No statistically significant difference was found among treatments. Therefore, adding cyclophosphamide or daunorubicin, or using the COAP regimen with continuously infused cytarabine, produced no significant improvement over previously reported regimens. There was no significant difference in remission lengths in previously untreated AML patients maintained on OAP (median 81 weeks) or COAP (median 65 weeks).