Spectral study of E.E.G. activity under enflurane anaesthesia shows a mild and early increase in global power distributed over the whole spectrum up to 20 c/sec, initially without dominant activity. Slow activity at 4-6 c/sec occurs later and gradually becomes slower, although without providing what could be called a specific pattern. These results have been compared with the same spectral analysis approach in anoxia in the normal subject and in epileptic subjects. Our experience so far does not allow the identification of the discharges observed the enflurane as epileptic discharge.