Neuropeptide, substance P, in the sensory nerve ending, recently known to be present in the nasal mucosa, induces vasodilation, plasma extravasation and sneezing reflex. This substance P in unmyelinated C fiber is depleted by capsaicin, pungent ingredients in red pepper, upon local application to the nasal mucosa. In order to investigate the effect of capsaicin to the hyperreactive nasal symptoms, authors observed the change of substance P immunoreactive nerve fiber with immunohistochemical method and the change of neurogenic inflammation and sneezing reflex with fluorescence microscope and spectrophotometry after capsaicin application, and the following results were obtained. 1) After local application of capsaicin, substance P immunoreactivity was partially disappeared in nasal mucosa. 2) The extravasated Evans blue(20mg/kg) was stronger morphologically in the group of electrical and capsaicin stimulation than that in the control and capsaicin pretreated group. 3) The amount of the extravasated Evans blue measured with the spectrophotometry was increased in the group of local capsaicin stimulation more than in the control group and capsaicin pretreated group. 4) The frequency of sneezing reflex was increased in the group of local capsaicin stimulation more than that in capsaicin pretreated group.