In 12 patients suffering from chronic idiopathic anal pain, the rectosphincteric function was studied using manometric and x-ray techniques. The results of manometric investigations were compared with those obtained in 12 healthy volunteers. In all patients, the resting pressure in the anal canal was significantly higher than in control subjects. In 10 patients, defecography revealed abnormalities of the pelvic muscles. We treated the patients by using biofeedback techniques, consisting of voluntary modifications of the state of contraction of the external sphincter. In all cases, pain disappeared after a mean of eight biofeedback training sessions. When noxious manifestations had disappeared, manometry showed a significant decrease in the anal canal resting pressure. Our results indicate 1) that chronic idiopathic anal pain is associated with abnormal anorectal manometric profiles, probably resulting from a dysfunctioning of the striated external anal sphincter, and 2) that biofeedback training is an effective treatment for chronic idiopathic anal pain.