Objective: To examine the epidemiology of primary biliary cirrhosis (PBC) in Finland and to evaluate whether the possible increase in prevalence was attributable to the increasing incidence, better survival, or both., Material and Methods: The Hospital Discharge Register, pathology registers, and death certificates for the years 1988 99 were scrutinized, and the patients identified were followed-up for survival until 31 October 2004. The study area covered four university hospital districts: a total of 25 hospitals. The diagnosis of PBC was regarded as definite (or probable) if three (or two) of the following criteria were fulfilled: positive antimitochondrial antibodies, constantly elevated alkaline phosphatase, and compatible liver histology., Results: In the total population of the study areas, the age-standardized prevalence of PBC increased during the study period from 103 (95% CI: 97-110) to 180 (172-189) per million inhabitants. Incidence increased from 12 (10-14) to 17 (15-20) per million inhabitants per year. The annual average increase in prevalence was 5.1% (4.2-5.9%, p <0.0001) and in incidence 3.5% (0.9%-6.0%, p =0.008). In gender-specific analyses among women, the prevalence of PBC increased from 161 (151-171) to 292 (277-207) per million during the study period and the incidence from 20 (16-24) to 27 (23-32) per million per year. The death rate was 4% per year and half the deaths were from liver-related causes. Survival after diagnosis during the study period lengthened., Conclusions: The prevalence of PBC increased in Finland during 1988-99, owing to both the increased incidence and the prolonged survival.