There is a strange disease called proctalgia fugax in which rather uncomfortable pain appears suddenly mostly at night without any particular warning and disappears completely without any objective traces. It also is categorized as a functional anorectal pain under the Rome II (diagnostic criteria for the functional gastrointestinal disorders). For the causes, many theories have been advocated but not decisive and therefore were not linked to the definite treatment. The author experienced 68 patients with proctalgia fugax, among which 55 patients had tenderness along the pudendal nerve. The location, character, and degree of pain caused by digital examination were confirmed by all of them to be similar to that which they experience at times of paroxysm. After administration of a nerve block, symptoms disappeared completely in 65 percent of the patients and decreased in 25 percent. These data suggest that the pathogenesis of proctalgia fugax is neuralgia of the pudendal nerves.