Pulmonary edema is a rare complication of distance running. All 4 previously reported cases occurred after triathalons or ultramarathons. We report the first case of pulmonary edema in a healthy but untrained runner after a conventional 42-km marathon race. This is also the first reported case of pulmonary edema complicating distance running in which hemodynamic measurements have been made. The pulmonary capillary wedge pressure was low. The cardiac index was initially depressed, and the arterial-venous oxygen tension difference was high, but the latter abnormalities disappeared after volume infusion. These hemodynamic data suggest that pulmonary edema in this distance runner was predominantly noncardiogenic. The etiology of the edema is uncertain, but concurrent hyponatremia and cerebral edema were present in this patient, as in 2 previously reported cases, suggesting that neurogenic pulmonary edema caused by water intoxication may be a contributing factor in pathogenesis.