we described a patient with acute promyelocytic leucemia (apl) who developed all-trans retinoic acid syndrome (atras). atras presents in patients with apl treated with all-trans retinoic acid (atra). it has an incidence from 5-27% with mortality of 29%. atras clinical manifestations are fever, hypotension, respiratory, renal and hepatic insufficiency, lung infiltrates, pleural and pericardic efussion, and generalized edema. it is secondary to atra effect on promyelocyte differentiation, which causes systemic inflammatory response syndrome, endothelium damage with increase in capillary permeability, microcirculation obstruction, and tissue infiltration. treatment is based on atra suspension, steroids and support measures.