Microlithiasis has been proposed as a cause of both occult gallbladder disease and of idiopathic pancreatitis. Theoretically, microlithiasis could also cause postcholecystectomy pain by causing temporary biliary obstruction and may be more common in patients with sphincter of Oddi dysfunction. The frequency of crystals in bile duct aspirates was assessed from patients with symptoms after cholecystectomy with and without elevated baseline sphincter of Oddi pressures.