OBJECTIVES: I. Determine the rate of response (complete or partial remission), duration of response, relapse free survival, and overall survival of patients with relapsed or refractory acute myeloid leukemia (AML) or untreated older patients or those with secondary AML when treated with arsenic trioxide. II. Evaluate the toxicities of this agent in this patient population. III. Measure degree of apoptosis induced and/or differentiation in pretreatment and posttreatment AML cells.