For patients with acute promyelocytic leukaemia (APL), all-trans retinoic acid (ATRA) and chemotherapy is the standard of care. A multicentre, phase III trial has now compared ATRA plus chemotherapy with ATRA plus arsenic trioxide for low-to-intermediate risk patients with APL. The ATRA plus arsenic trioxide regimen demonstrated non-inferiority compared with standard therapy and was associated with less haematological toxicity and fewer infections, but greater hepatic toxicity.