Total or subtotal colectomy is the surgical treatment of choice for patients with ulcerative colitis. Recently it has been reported that colectomy may lead to increased lithogenicity of bile, short nucleation time, cholesterol crystal formation, and gallstone disease. We examined whether colectomy in patients with ulcerative colitis leads to changes in bile composition that predisposes to cholesterol crystal formation and cholesterol gallstone disease. Ten consecutive patients who had previously undergone ileostomy and colectomy because of ulcerative colitis were admitted for ileal pouch surgery. At operation bile was obtained by puncture of the gallbladder. Controls were 35 patients undergoing cholecystectomy (23 for cholesterol gallstone disease and 12 for reasons other than gallstone disease). The gallbladder bile was analyzed for cholesterol crystals, bile acid, and biliary lipid composition, cholesterol saturation, and nucleation time. The colectomized patients had normal biliary lipid composition, normal cholesterol saturation, and normal nucleation time, in contrast to gallstone patients who displayed highly supersaturated bile with a short nucleation time. Thus patients with ileostomy after colectomy because of ulcerative colitis have normal cholesterol saturation and nucleation time of bile.