OUTLINE: This is a multicenter study. Patients receive arsenic trioxide IV over 1-2 hours daily for up to 60 days. After 4-6 weeks of rest, patients receive up to 5 additional courses of therapy of 25 days each followed by 4-6 weeks of rest. Patients with a complete response (CR) receive 1 additional course of 25 days after achieving CR. Treatment continues in the absence of unacceptable toxicity or disease progression. Patients are followed monthly for 6 months, every 2 months for 6 months, every 3 months for 12 months, and then every 6 months thereafter.