Acute chest syndrome is an affection, specially in young adults, of sickle cell disease and is responsible for 25% of the deaths. The authors report the case of an alcoholic 45-year-old mulatto man, without any previous manifestation of sickle cell disease, who presented with a pneumonia-like clinical picture with seven days of duration. The chest X-ray revealed bilateral lung infiltrates and spots of consolidation with air bronchograms, and left pleural effusion. The patient also had anemia and leukocytosis with neutrophilia. Treated with cefoxitin and amicacin, the patient developed acute respiratory insufficiency and died 14 hours after hospitalization. The necropsy showed lungs with intense congestion, intra-alveolar hemorrhage, diffuse alveolar damage, and sickle red blood cells. The progressive, fast, and severe character of the acute chest syndrome, which is frequently mimicked by other illnesses, makes the disease a dramatic and severe event of difficult earlier diagnosis. Therefore, in countries like Brazil, with a large black population, the physicians must always be aware of this possibility.