Signal averaging of visually evoked cortical potentials was done on Wistar strain rats during recovery from nembutal (sodium pentobarbital) anesthesia. Several studies (Dafny, 1978; Gines et al., 1963; Roig et al., 1961) have shown significant differences between recordings from unanesthetized rats and from rats anesthetized with various agents. The purpose of this study was to evaluate changes in the cortical response throughout an eight hour nembutal recovery period in order to determine the feasibility of using a signal averaging technique for classification of anesthetic depth. The results of this study show that the recovery from nembutal anesthesia is characterized by three major changes in the cortical response: the presence or absence of the secondary response component, the appearance of desynchronized cortical firing and a change in the latency of the individual component peaks. Using these neurophysiological signs, the rate of recovery from nembutal anesthesia can be described and quantified. The characterization of these changes will provide future researchers with a tool to evaluate electrophysiologically the usefulness of various treatments at altering the rate of recovery from anesthesia.