Of 93 consecutively treated patients with acute myeloid leukemia 36 (39%) achieved complete remission (CR). Thirty-five patients were randomized to receive either maintenance chemotherapy alone (C) or a combination of active nonspecific immunotherapy with Corynebacterium parvum and chemotherapy (C + I). Maintenance therapy was given monthly for 1 year or until relapse. The median survival time was 21 months for patients treated with chemotherapy alone, compared with 30 months for patients treated with chemotherapy and immunotherapy. The median remission duration was 15 months for patients treated with chemotherapy, compared with 18 months for chemotherapy and immunotherapy group. While no statistically significant difference in remission duration or survival time could be attributed to the use of immune stimulation, a plateau of 40% long-term time survivors was defined in the chemotherapy and immunotherapy group. Age and sex were found to be the major prognostic factors for achievement of CR. No difference was found in remission duration or survival between the two different induction schedules. Neither did the morphological subtype of AML (FAB classification) or the leukocyte count at diagnosis correlate with remission rate or survival.