We evaluated the gallbladders of 121 patients who had well-documented primary sclerosing cholangitis. Sonograms, cholangiograms, and CT scans were reviewed, and the findings were correlated with surgical or autopsy findings, when available. Pathologic examination of the gallbladder was available in 55 (45%) of the 121 patients; of these, 49 (89%) had abnormal gallbladders. Ninety-three of the 121 patients had one or more radiologic examinations of the gallbladder: 77 had sonograms, 80 had cholangiograms, and 18 had CT scans. Seventy-five (62%) of the 121 patients had abnormal gallbladders on histologic examination or had positive findings on one or more imaging study. By excluding 25 patients who had histologic changes of borderline significance and/or patients who had thick-walled gallbladders attributable to end-stage liver disease, we concluded that 50 (41%) of the 121 patients had intrinsic abnormalities of the gallbladder. Thirty-two (26%) had gallstones, 18 (15%) had probable primary sclerosing cholangitis involving the gallbladder, and five (4%) had benign or malignant neoplasms. Our study indicates that gallbladder abnormalities are common among patients with primary sclerosing cholangitis, and sonography is the most useful technique for evaluating these conditions.