Although severe pulmonary edema is encountered occasionally in patients needing CPR, there has been no definitive description on the mortality and morbidity of pulmonary edema after CPR. The author experienced severe pulmonary edema after standard CPR in 20 of 71 patients who suffered sudden, unexpected cardiac arrest and regained heart function by CPR. The varied onset of pulmonary edema, which may have developed when massive pink frothy secretions exited from the endotracheal tube, ranged from a few minutes to 45 min after the re-establishment of heart beat. These 20 patients showed a significantly higher P(A-a)O2, insignificant lower plasma protein concentrations, and high plasma osmolarities as compared with those who did not develop pulmonary edema. Only 2 patients with pulmonary edema survived. During CPR, many factors could cause pulmonary edema, including external cardiac massage (ECM), administration or release of catecholamines, hypoxia, acidosis, overhydration, etc. This study indicates that patients who need CPR have a high likelihood of developing pulmonary edema.