The clinical profile of primary biliary cirrhosis in Japan was clarified on the basis of data on 1066 patients attending 212 hospitals and institutions in this country. Six hundred and twelve patients (57.4%) were asymptomatic. The majority of the patients were middle-aged women. Pruritus was the most frequent initial symptom of symptomatic primary biliary cirrhosis. Antimitochondrial antibodies were positive in 877 patients (82.5%). Sjögren's syndrome was the most common associated autoimmune disease. Liver biopsy was performed in 753 patients at the time of diagnosis, and histological staging by Scheuer's classification indicated that 307 (43.7%) patients were in stage I and 222 (31.6%) were in stage II. The most frequent causes of death were hepatic failure and/or gastrointestinal bleeding, which affected 166 (78.3%) of the 212 patients who died. Statistical analysis using Cox's regression method revealed that the patient's age and the serum bilirubin, albumin, and total cholesterol concentrations were significant predictors of the prognosis. A prognostic index was also calculated that could be used to predict the duration of survival for patients with primary biliary cirrhosis.