All-trans-retinoic acid represents a major progress that has made acute promyelocytic leukemia the most curable subtype of acute myeloid leukemia in adults. Although all-trans-retinoic acid is usually well tolerated, some patients develop the retinoic acid syndrome, characterized by unexplained fever, weight gain, respiratory distress, interstitial pulmonary infiltrates, pleural and pericardial effusions, episodic hypotension, and acute renal failure. Further studies of growth factor expression and modulation of adhesion molecules are warranted to provide further insights into the pathogenesis of the syndrome and may lead to its prevention.