OBJECTIVE: The efficacy of endoscopic treatment of sphincter of Oddi dysfunction (SOD) with endoscopic sphincterotomy (ES) remains controversial. Although some studies have shown a positive impact on patient symptoms after treatment, these reports have been largely qualitative and evaluated on short-term response. The aim of our study was to quantitatively measure the long-term outcomes of endoscopic therapy in patients with SOD. METHODS: Thirty-three patients with suspected SOD underwent selective sphincter of Oddi manometry (SOM) of the biliary and/or pancreatic sphincter. Each patient completed a telephone-based survey measuring symptomatic pain before and after SOM ± ES. The questioner was blinded to the results of SOM. The patients with normal SOM or SOD but who did not undergo ES served as controls. RESULTS: Of these 33 patients (27 women, mean age 48.7 yr, range 13-74), 19 (57.5%) were found to have SOD (12 biliary, six pancreatic, one both). The average follow-up was 18.1 months (range 7-34). Of the patients with SOD, 17 (89%) underwent ES. At follow-up of the 19 patients undergoing ES, five were taking narcotics for persistent pain, two were taking antidepressants, and 15 identified the endoscopic therapy as the reason for their relief. Of the 14 controls, seven were taking narcotics, seven were taking antidepressants, and two identified the endoscopy as the reason for their relief; some patients were taking both antidepressants and narcotics. CONCLUSIONS: Patients found to have SOD who undergo ES are more likely to be improved on long-term follow-up when compared with patients with suspected SOD but normal manometry without ES. However, almost uniformly, despite ES, patients continue to have pain, which is consistent with most chronic pain disorders and which suggests a multifactorial cause for the pain. © 2003 by Am. Coll. of Gastroenterology.