OUTLINE: Patients receive arsenic trioxide intravenous (IV) over 2 hours either daily for 15 consecutive days or 5 days on, 2 days off for a total of 15 doses. Treatment repeats every 2-5 weeks after the previous course for a maximum of 12 courses in the absence of disease progression or unacceptable toxicity. Patients achieving complete remission are followed every month for 3 months, every 2 months for 6 months, every 3-4 months for 1 year, and then every 6 months thereafter. All other patients are followed every 3 months for 1 year and then annually thereafter.