A computer-based automated system forcontinuous unattended monitoring of evoked potentials, EEG, transcranial impedance, and transthoracic impedanceas well as conventional parameters, was developed for use in the neurosurgical intensive care unit. A total of 50 patients has been studied. In the initial phases of the program, only evoked potentials were monitored. As the program evolved, additional variables were added. Transcranial impedance measurements have potential for detection of asymmetries and space-occupying lesions. Transthoracic impedance measurements provide a convenient means for monitoring respiration rate and tidal volume, and have value for detecting intrathoracic fluid accumulation. The technical feasibility of unattended monitoring of EEG and evoked potentials has been demonstrated. In patients who were disoriented, but conscious, evoked potentials were stable. In patients with unstable neurologic status, evoked potentials showed considerable variability with time. A peak-detection algorithm was developed for on-line EEG monitoring, and a statistical-tracking procedure was implemented for detecting significant changes in EEG parameters. In general, lower-percentage delta-activity and higher mean-frequency correlated with increased responsiveness. In some patients, changes in evoked potentials and EEG were observed prior to observable neurologic changes. The study suggests that the non-invasive techniques under study have potential for detection of adverse trends, and as such may provide adjuncts for neurosurgical intensive care monitoring.