To evaluate whether hypofunction of the sympathetic nervous system induced by long-term reserpine treatment affects the parasympathetic system in the nasal mucosa in the receptor level, a receptor binding assay was performed using the nasal mucosa of guinea pigs which had chemical denervation produced by intraperitoneal injection of 0.1 mg/body reserpine once daily for 4 weeks. The maximum number of muscarinic cholinergic receptor bindings to diquinuclidinyl benzilate (3H-QNB) in the nasal mucosa of the reserpine-treated guinea pigs was increased by 46% as compared with that in the control (p < 0.05). The present experiment shows that hypofunction of the sympathetic system in the nasal mucosa induced by reserpine may affect the parasympathetic system in the nasal mucosa.