Study objective: To characterize adult patients with acute lung injury complicating severe imported Plasmodium falciparum malaria. Design and setting: Retrospective study of patients with severe P falciparum malaria admitted to the medical ICU of a university hospital infectious diseases department. Patients: Forty adults with complicated malaria, with (group 1, 12 patients) or without (group 2, 28 patients) acute lung injury. Results: patients with acute lung injury had a higher simplified acute physiology score on admission (24.2+/-3.2 vs 13.71+/-0.7 in group 2, p<0.0001) and a longer time interval to adequate antimalarial therapy (8.8+/-2.5 vs 4.9+/-0.6 days in group 2, p=0.046), Of the nine group 1 patients given mechanical ventilation, eight had a PaO2/FIo(2) less than or equal to 200 mm Hg. Two patients with moderate hypoxemia received oxygen through a nasal tube and one received continuous positive airway pressure via a face mask. Acute renal failure, unrousable coma, metabolic acidosis, and shock were significantly more common among group 1 patients. The number of complications of malaria was significantly higher in patients with acute lung injury (4.7+/-0.5 vs 1.6+/-0.1 in group 2, p<0.0001). Five patients, including four with acute lung injury, had evidence of bacterial infection (pneumonia or primary bacteremia) at ICU admission, Four patients with acute lung injury died (33%) vs one patient without acute lung injury (4%, p=0.022). Conclusions: Acute lung injury is more likely to occur in patients with extremely severe, multisystemic P falciparum malaria. In patients with acute lung injury and septic shock, bacterial coinfection should be suspected and treated empirically since it contributes substantially to early mortality.