A series of experiments was devised to simulate the 3 types of drowning believed to occur in humans. Obstructive asphyxia (simulating laryngospasm) beyond the cessation of efforts to breathe was successfully treated with intermittent positive pressure ventilation with air. When the lungs were flooded with sea water after a comparable period of asphyxia, intermittent positive pressure ventilation delayed pulmonary edema and death. Prolonged positive pressure ventilation with 100% oxygen and the infusion of plasma resulted in survival. Flooding of the lungs with fresh water after asphyxia resulted in sudden ventricular fibrillation. Closed chest cardiac massage combined with intermittent positive pressure ventilation with 100% oxygen was followed by external defibrillation and the restoration of effective circulation.