We have experienced six patients with postexercise syncope. No specific abnormalities were found in any of the patients from echocardiographies or from the electrophysiologic studies performed on three of them. Syncope occurred in the early recovery period following exercise tests. One patient showed transient complete AV block with a very slow escape rhythm. The others showed sinus exit blocks or sinus pauses. These ECG abnormalities were not reproduced unless the amount of exercise reached near that of the previous tests. An excessive vagal reaction, secondary to augmented sympathetic stimulation, has been proposed as the causal mechanism. In patients with a history of syncope during recovery after exercise, education to avoid excessive exercise with or without betablockade was enough for its prevention.