OBJECTIVES-Although autoimmune diseases can have a significant impact on the quality of life, there has been a relative paucity of data with respect to the functional status of patients with primary biliary cirrhosis (PBC).METHODS-We conducted a case-control study of 182 patients ("cases") with PBC as well as 225 age-and sex-matched friend control subjects using a standardized instrument obtained from the National Health and Nutrition Examination Survey.RESULTS-In all, 126 of 182 cases (69%) and 141 of 225 friend controls (62.6%) responded to this survey, a response rate comparable to or better than in similar previous studies of such instruments. Patients with PBC had a significantly reduced functional status score compared to their controls (p < 0.001). Interestingly, a lower level of education and the presence of arthritis and hypertension were significantly associated with these lower levels of functional capabilities. These data were subjected to multivariate analysis and confirmed. Age was not associated with impaired functional status in either the patients or controls.CONCLUSIONS-Studies of this nature have potential implications for the well-being and management of patients with PBC, and focus on issues that can be addressed to help maintain functional status in this chronic disease.