Of 50 consecutive patients admitted with acute myelogenous leukemia, 30 developed complete remissions on antileukemic therapy. Nineteen of the 30 repeatedly had elevated serum glutamic oxalacetic transaminase (SGOT) concentrations 3 to 14 weeks after the start of therapy. Patients with SGOT elevations had a significantly greater chance of remission and a longer survival (76 ± 11 weeks) than those with normal SGOT levels (39 ± 5 weeks), suggesting that hepatitis may have a beneficial effect in acute myelogenous leukemia. The hepatitis was mild in all patients. Review of patients at this institution alive 2 years after the diagnosis of acute myelogenous leukemia showed that they repeatedly had elevated SGOT levels. We believe that most had non-A, non-B post-transfusion hepatitis, which may have a beneficial effect on the leukemia or serve as an indicator of patients who have greater immunocompetence and thus a better prognosis.