Fifty‐one adult patients with acute nonlymphocytic leukemia (excluding acute promyelocytic leukemia) were treated on the L‐12 protocol. The L‐12 differed from the preceding L‐6 in that 2,2‐anhydro‐1‐B‐D‐arabinofuranosyl‐5‐fluorocytosine (AAFC), replaced arabinosylcytosine (ara‐C) together with 6‐thioguanine (TG) for remission induction. Achievement of remission was followed by an extended 14‐week multi‐drug consolidation program. With this more intense regimen, an overall complete remission rate of 49% and a median remission duration of 23.7 months were achieved; these results were not significantly better than the 57% complete remission rate and 8.6 months median remission duration obtained with the L‐6 regimen. Four year disease‐free survival was 22% on the L‐12 compared with 16% on the L‐6 protocol. No relationship between prognosis and FAB classification was found on either the L‐6 or the L‐12 protocol.