Two experiments were designed to investigate a below-zero habituation of the skin resistance reflex (SRR) component of the orienting reflex to auditory stimuli. In both experiments, subjects were given additional ten stimulus-presentations immediately after initial habituation (extended habituation, EH procedure), and they were compared with those without EH procedure. Effects of EH procedure upon rehabituation and SRRs to novel stimuli (Experiment I), and upon SRRs to novel stimuli under an additional control condition (Experiment II), were examined. The EH procedure enhanced SRRs to novel stimuli and had no effects on the spontaneous recovery. These results suggested that habituation would not proceed beyond the zero-level by the EH procedure.