The Eastern Cooperative Oncology Group conducted a randomized study to determine the efficacy of consolidation therapy in prolonging the duration of complete remission (CR) in adults with acute nonlymphocytic leukemia (ANLL). Induction chemotherapy with daunorubicin, cytosine arabinoside, and 6-thioguanine (DAT) yielded CR in 65% of 283 patients with ANLL, aged 16–69. For patients aged 60–69, the CR rate was 58%. Of 184 patients in CR, 146 patients were then randomized to receive either maintenance therapy with weekly cytosine arabinoside and 6-thioguanine alone (69 patients) or two courses of reduced doses of DAT 1 mo apart, before commencing the same maintenance program (77 patients). Consolidation therapy resulted in hematologic toxicity, but was not lethal in any of the eligible patients. Patients receiving consolidation plus maintenance therapy experienced a longer CR duration (40 wk) and disease-free survival at 2 yr (28%) than did those patients receiving maintenance therapy alone (34 wk and 14%, respectively). These differences are not statistically significant. These results suggest that approaches to consolidation therapy employing reduced doses of the induction therapy regimen can have, at best, only a small benefit. For consolidation therapy to provide substantial improvement in CR duration, intensive regimens with non-cross-resistant drugs will be required.