Monocrotaline, a plant alkaloid shown histologically to produce pulmonary endothelial damage and edema, was used in dogs to produce an acute model of noncardiogenic pulmonary edema. Following intravenous injection there was no change in pulmonary vascular pressures or heart rate; cardiac output fell and pulmonary vascular resistance increased. After 2 h measurement of lung water demonstrated modest pulmonary edema in all animals. The degree of edema produced was more consistent and reproducible than that following alloxan or alpha-naphthylthiourea.