Peroperative epicardial mapping of activation, recovery and activation-recovery intervals in the human heart has been performed in a group of 12 patients. These patients had the coronary disease but electrocardiograms with normal characteristics. For this mapping, 240 unipolar electrograms were simultaneously recorded with the system SATAPEC built in our laboratory. The results confirm the classical data obtained on the dog heart. In particular, it was well established that the duration of activation corresponding to activation-recovery intervals is shorter at the base than at the apex of the posterior surface of the heart. With SATAPEC it is very easy to obtain epicardial mapping of electrical activity in a few minutes during open heart surgery.