In this Southwest Oncology Group (SWOG) study, 216 adults with acute leukemia were treated with ten-day chemotherapy consisting of vincristine sulfate (Oncovin), cytarabine (ara-C) (100 mg per square meter of body area per day by 24-hour infusion), and prednisone (ten-day OAP). The results were compared with those of a previous SWOG study in which cytarabine (200 mg per square meter of body area per day) was given for five days (five-day OAP). Patients entering complete remission (CR) were given three consolidation courses of five-day OAP and randomized to maintenance chemotherapy alone (32 patients) or combined with BCG vaccine (24 patients). For 160 previously untreated patients with acute myelogenous leukemia, there was no difference in remission rates (53% vs 43%) or median survival times (48 vs 47 weeks) between ten-day and five-day OAP. The difference in duration of CR (74 vs 54 weeks, respectively) between the two maintenance arms was not statistically significant. However, 14% of evaluable patients with acute myelogenous leukemia and 26% of those achieving CR were alive and in remission more than five years.