Recordings were electroencephalographical (EEG with spectral analysis), polygraphical (EMG, EKG, breathing). Visual and Auditory Cerebral Evoked Responses were also recorded. The depth of narcosis was quantified upon EEG data. The reactivity during the narcosis and the mechanisms of action of Etomidate on the "non specific structures" are discussed. Cautions should be taken with the use of tomidate in anesthesiology with epileptic and arteriopathic patients.