Five hundred forty three adult patients with acute leukemia were entered on the study designed to: (1) test efficacy of vincristine and prednisone used as primary drug therapy in patients with good prognosis as judged by a circulating blast cell count less than 30,000 cm2; (2) investigate the use of either simultaneously or sequentially administered Adriamycin plus cytosine arabinoside plus vincristine and prednisone; and (3) to assess the use of bacillus Calmette-Guerin (BCG) in the maintenance phase on both the response and duration of response. Complete remissions were seen in 21% of patients with the vincristine and prednisone arm. Complete remission rates were similar in both the simultaneously and sequentially administered chemotherapy with overall complete remission rates of 55%. Median durations of complete remission and survival were 35 and 62 weeks, respectively, for patients with AML; and 47 and 75, respectively, for patients with ALL. Toxicity was within acceptable limits. BCG administered during the maintenance phase of therapy caused no differences in duration of complete remission and survival. These results demonstrate an improved response and duration of response over previous studies done by this group.