In an attempt to reduce the risk of leukemic relapse, different post-remission intensifications based on high-dose Ara-C (HiDAC) and autologous bone marrow transplantation (ABMT) were evaluated in patients with acute non lymphocytic leukemia in first remission and compared as to response and toxicity. Between September, 1985 and May, 1987, 34 patients in complete remission were eligible for our study. Induction therapy consisted of one or two courses of daunorubicin (DNR) and Ara-C (schedule 3 + 7). Fourteen patients receiving intensive post-remission chemotherapy with DNR + Ara-C (schedule 2 + 5), HiDAC + DNR, and ABMT following pretransplant BAVC conditioning entered the first pilot study. A high toxicity was observed and only 5 of them completed the full treatment plan. Thus the second pilot study used a single post-remission intensive course with HiDAC + m-AMSA and ABMT following cyclophosphamide plus TBI or BAVC. This approach was more feasible. The preliminary results show the usefulness of intensive post-remission therapy: in fact, all patients but one who completed the treatment program are still in continuous complete remission. A large number of patients and a longer follow-up are required to draw final conclusions.