Seventeen patients, 15 women and 2 men with upper abdominal pain categorized to biliary group I suspected sphincter of Oddi dysfunction, underwent thorough clinical evaluation including ERCP and endoscopic sphincter of Oddi manometry. All the patients were subsequently treated by endoscopic (n = 15) or surgical (n = 2) sphincterotomy. The mean age of patients studied was 62 years. They all had cholecystectomy several years previously (median, 18 years). At ERCP all patients showed a large common bile duct dilation (mean diameter, 18 mm) and delayed contrast drainage greater than 45 minutes. Sphincter of Oddi manometry, although abnormal in most patients, revealed normal sphincter of Oddi pressure in six patients (35%). Nonetheless, sphincterotomy resulted in relief of symptoms in all (mean follow-up, 28 months; range, 3 to 46 months), thus suggesting that their pain was indeed caused by the disordered sphincter of Oddi. These findings support the previous assumption that in symptomatic post-cholecystectomy patients the triad of elevated liver function tests, dilated common bile duct, and delayed contrast drainage at endoscopic retrograde cholangiopancreatography indicates a definitive sphincter of Oddi abnormality. The normal sphincter of Oddi pressures in many of these patients are probably due to a different, noncompliant type of sphincter of Oddi dysfunction. Because these patients invariably benefit from sphincterotomy, sphincter of Oddi manometry in this category is not only unnecessary, but it may also be misleading.