Capsaicin, a nonenamide derived from Capsicum plants, has proven useful in patients with vasomotor rhinitis. In the present study, we studied the effects of 15 micrograms capsaicin suspended in 100 microliters solution in patients with known vasomotor rhinitis. Drug was given 3 times/day for 3 days to each patient by means of a spray delivered to the nasal mucosa. Acute effects induced by the drug included painful sensation and secretion of nasal fluid but were no longer observed at the last capsaicin application. Patients recorded their symptoms over a 1-month period. The mean symptom score involving nasal obstruction and nasal secretion was markedly reduced by capsaicin treatment. We advance the hypothesis that the beneficial effect of drug treatment may be due to its specific action on the peripheral endings of primary sensory neurons leading to their functional blockade. Further randomized, double-blind, placebo-controlled trial is now needed.