Neurogenic inflammation is characterized by the vasodilation, plasma extravasation and edema formation due to released nueropeptide from the sensory nerve endings by the various stimulations such as capsaicin and electric stimuli. Ruthenium red is an inorganic polycationic dye which has a blocking effect on the cation channel in the sensory nerve terminals and has been considered as a blocker of the neurogenic inflammation. The purpose of this study is to investigate the effect of the ruthenium red on the neurogenic inflammation in the rat nasal mucosa induced by various stimulations. The amount of plasma extravasation was used as a parameter of the neurogenic inflammation and measured by the Evans blue extraction. Thr pretreated ruthenium red inhibited the effect of the capsaicin on neurogenic inflammation dose-dependently, but had no effects on the substance P and hypertonic saline-induced neurogenic inflammation. According to our results, ruthenium red might be utilized as a tool for the sensory neuron research and treatment of the nasal hyperreactivity.