We studied 33 patients with primary biliary cirrhosis representative of a well-defined population (240,000) during the decade 1973-82. Mean annual incidence was 13.7 per 10(6) and point prevalence, 92 per 10(6) inhabitants in 1982. An accumulation of asymptomatic cases, constituting 45% of all patients, with a normal life expectancy accounted for this high prevalence. During the study period no disease progress was seen in asymptomatic patients, in contrast to a 50% mortality in the symptomatic group. Disease progress in the latter group was reflected by deterioration of N-demethylating capacity and increasing bilirubin levels. Although our data confirm an increasing prevalence of primary biliary cirrhosis, the mortality rate during the study period was almost identical to that in an earlier period, 1951-60.