Psychophysiological anomalies in symptomatic schizophrenic patients, remitted schizophrenic patients, and individuals at heightened risk for a schizophrenic disorder are reviewed with an emphasis on electrodermal anomalies. Two electrodermal anomalies are identified in different subgroups of symptomatic patients: (1) an abnormally high sympathetic arousal and (2) an abnormal absence of skin conductance orienting responses to innocuous environmental stimuli. The same two electrodermal anomalies also have been observed in remitted schizophrenic patients. Among high-risk individuals, the offspring of schizophrenic patients display abnormally high electrodermal responsiveness to aversive stimulation, whereas a substantial proportion of college students who score high on physical anhedonia (a putative risk factor for schizophrenia) exhibit skin conductance nonresponsiveness. Thus, heightened sensitivity to aversive stimulation appears to be associated with a genetic vulnerability to schizophrenia, while tonic hyperarousal , which occurs in subgroups of symptomatic and remitted schizophrenic patients, may reflect a later developmental consequence of the underlying vulnerability. Skin conductance nonresponsivity may represent a different developmental consequence associated with the same underlying vulnerability or it may represent a different type of vulnerability. Other psychophysiological anomalies also are promising indicators of the vulnerability to schizophrenia (e.g., deviant smooth pursuit eye movements, attenuated P300 component of the event-related brain potential, reduced electroencephalic (EEG) alpha activity, and heightened EEG delta activity).