 The objective of the present investigation is to analyze EEG and auditory evoked potentials at the transition from consciousness to unconsciousness and vice versa. A set of electroencephalographic and auditory evoked potential parameters should be identified that allows separation of consciousness from unconsciousness reflected by responsivenessunresponsiveness to command. The study is based on data of 80 patients undergoing general anesthesia with remifentanil and either sevoflurane or propofol. 