It is estimated that 11% of all patients requiring active intervention for acute upper airway obstruction develop negative-pressure pulmonary edema. This pathologic process typically has a benign and rapidly resolving clinical course with the prompt use of mechanical ventilation and positive end expiratory pressure. A review of the literature, however, has revealed a morbidity and mortality rate of 11% to 40% in reported series. During the years 1991 through 1993, six patients were identified in whom negative-pressure pulmonary edema developed after various otolaryngologic procedures. Five (84%) of the six patients had complete resolution of the pulmonary edema within 24 hours, and the sixth patient progressed to prolonged mechanical ventilation and eventual death. In an effort to further understand the pathophysiology of this disease, a cardiac evaluation was performed by use of echocardiography on all six patients. In three of the six patients, studies revealed an underlying cardiac anomaly not previously identified by history or physical examination. Findings included one case of hypertrophic cardiomyopathy and two cases of pulmonary and tricuspid valvular insufficiency. This 50% incidence of cardiac anomalies is striking, in contrast to the less than 1% incidence of these anomalies in the general adult population. To our knowledge, this is the first study to implicate an underlying cardiac cause for the generation of negative-pressure pulmonary edema. On the basis of this study, we recommend that echocardiography be a part of the routine evaluation of all patients who manifest negative-pressure pulmonary edema.