In this study of previously untreated adult acute lymphocytic leukemia (ALL) performed by the Eastern Cooperative Oncology Group, patients were randomized to induction therapy with either DVP (daunorubicin 45 mg/m2 daily, days 1, 2 and 3; prednisone 60 mg/m2 daily orally days 1-35; and vincristine 2 mg intravenously on days 1, 8, 15 and 22) or DATVP (daunorubicin 60 mg/m2 daily, days 1, 2 and 3; cytarabine 25 mg/m2 intravenous bolus followed by 200 mg/m2 daily as a continuous infusion on days 1-5; 6-thioguanine 100 mg/m2 orally every 12 h on days 1-5; vincristine 2 mg intravenously on days 1 and 8; and prednisone 60 mg/m2/day orally, days 1-7. Complete responders to both regimens received the same post-remission therapy, which consisted of a single course of cytarabine 3 gm/m2 infused over 1 h every 12 h for 12 doses. One month later those patients still in remission received six cycles of consolidation therapy with MACHO (cyclophosphamide 650 mg/m2, doxorubicin 40 mg/m2 vincristine 2mg all intravenously on day 1 with prednisone 100 mg/m2 orally daily on days 1-5. Methotrexate 200 mg/m2 intravenously and L-asparaginase 6000 U/m2 were given on day 22 and each course was given every 5 weeks. A single dose of intrathecal methotrexate was also given with each MACHO course. There were 276 evaluable patients randomized in this study. Complete response rates were 71% for DVP and 58% for DATVP. Median durations of complete response were 5.5 and 6.8 months, respectively. Median survival of all randomized patients was 14.4 months in each group. DATVP was more toxic than DVP. Intensification of treatment for adults with ALL may not improve outcome. Progress in the treatment of adults with ALL will require the identification of new agents for this neoplasm.