A previous report of depression of the galvanic skin response component of the orienting reaction after amygdalectomy despite behavioral deficits in habituation, prompted this study. Two frontal lobe lesions were investigated for effect on GSR reactivity to tones. The lateral frontal cortex lesion was found to depress the GSR orienting reaction whereas the medial-frontal-anterior cingulate lesion did not. Additional analysis of the control records in terms of lability-stability ratings showed that the lateral frontal Ss maintained a level of reaction lower than that of initially stabile or “rerun” stabilized controls. The conclusion of the previous report, i.e. that autonomic indicators of orienting may serve as a registration component of the behavioral reaction to novelty is supported and extended.