A 57-year-old man who had been intermittently taking one 300-mg tablet of quinine sulfate orally for leg cramps experienced transient acute pulmonary edema and hypotension 30-40 minutes after ingestion on two consecutive occasions. He was not taking any concomitant drugs, and there was no alternative explanation for either event. Serial troponin T tests and electrocardiograms, obtained on admission to the hospital, followed by an outpatient echocardiogram and a coronary angiogram, were essentially normal. We compared this case with one previously published and nine previously unpublished reports of quinine-associated pulmonary edema and conclude that some cases of pulmonary edema or adult respiratory distress syndrome in patients with malaria may be caused by an adverse reaction to quinine. Although infrequent, clinicians should be aware of this potentially serious and costly adverse reaction.