Remission induction therapy with 6MP and adriamycin in combination was administered to 19 adult leukemic patients refractory to previous therapy. Eight patients also received vincristine and prednisone. Thirteen patients had acute myelogenous leukemia, 3 undifferentiated leukemia, and 3 blastic transformation of chronic myelogenous leukemia. Four patients achieved remission but in only 2 were the remissions complete. Eleven patients failed to respond. Ten of the 19 patients developed unexpected severe liver toxicity manifested by a clinical picture of cholestasis (in the majority) or ascending cholangitis (in 2 patients). In the postmortem examination of 8 patients there was cholestasis and mild to severe hepatocellular damage in all.