Twelve informed and consenting patients were studied to determine the influence of capsaicin, the pungent component of the red pepper, on trigeminal neuralgia. All of these patients had idiopathic trigeminal neuralgia. These patients were followed up for 1 yr after the topical application over the painful area of 1.0 g of capsaicin three times a day for several days. Six patients had complete and four patients had partial relief of pain; the remaining two patients had no relief of pain. Of the 10 patients who were responsive to therapy, four had relapses of pain in 95-149 days. There were no relapses following the second therapy for the remainder of the year. We conclude that the topical application of capsaicin is frequently successful in relieving the pain from trigeminal neuralgia.