The effect of proctocolectomy on the primary sclerosing cholangitis that frequently is associated with chronic ulcerative colitis in patients with both conditions is unknown. We have studied prospectively the progression of clinical, biochemical, cholangiographic, and hepatic histologic features in 45 patients with both primary sclerosing cholangitis and chronic ulcerative colitis to compare these variables in the 20 patients who had undergone proctocolectomy with the 25 who had not. The two groups were similar initially with regard to clinical, biochemical, cholangiographic, and hepatic histologic findings. All patients were followed for a minimum of 1 yr and overall duration of follow-up was similar in both groups (4.1 vs. 3.9 yr). Clinically, new onset of hepatomegaly, splenomegaly, esophageal varices, and ascites did not differ in patients with and without proctocolectomy. Biochemically, the serial changes in bilirubin, alkaline phosphatase, aspartate aminotransferase, prothrombin time, and albumin were similar. Histologic progression on liver biopsy did not differ between groups, nor did changes on serial cholangiograms. Proctocolectomy also had no effect on survival. We conclude that proctocolectomy for chronic ulcerative colitis has no beneficial effect on the primary sclerosing cholangitis in patients with both diseases.