 INDUCTION THERAPY: Patients with standard and high risk APL receive tretinoin orally PO twice daily BID and arsenic trioxide intravenously IV over 2-4 hours on days 1-28. High risk APL patients also receive dexamethasone PO or IV BID on days 1-14 and idarubicin hydrochloride IV over 15 minutes on days 1, 3, 5, and 7. Patients achieving hematologic complete remission hCRhematologic complete remission with incomplete blood count recovery hCRi may go on to consolidation therapy. Patients who do not achieve hCRhCRi may continue treatment with tretinoin and arsenic trioxide for up to 70 days. 