Patients with renal failure and a creatinine clearance of less than 25 ml/min or requiring hemodialysis will be ineligible for the study. Otherwise, there are no rigid exclusion criteria based upon age, performance status, or co-morbidity. Decisions regarding enrollment of patients for whom these factors may be relevant will be individualized and left to the discretion of the investigators. Central venous access will be required for all patients. Patients of child-bearing potential must agree to use contraception during sexual intercourse while undergoing treatment with arsenic trioxide.