We describe a case of the sudden onset of cardiovascular collapse during emergence from anesthesia resulting from a massive venous air embolism, which was detected by transesophageal echocardiography. We present this case to remind anesthesiologists to be aware of the risk of a sudden return of air trapped in the venous system during emergence from anesthesia. The air is freed because the sympathetic tone is increased, muscle-pumping power is regained, ventilation shifts from positive-pressure to negative-pressure spontaneous ventilation, and the patient is repositioned after surgery.