The prognosis of patients with asymptomatic primary biliary cirrhosis has been uncertain. Cases of primary biliary cirrhosis in 95 patients from two centers are presented: 70 patients from a regional referral center (Freeman Hospital, FH) and 25 from an international tertiary referral center (King's College Hospital, KCH) with similar mean age at diagnosis and duration of follow-up (median, 12 months). During follow-up, 19 of 70 FH patients and 15 of 25 KCH patients developed symptoms (P less than 0.001); the mean time to symptom appearance was 43 months at FH and 35 months at KCH (P = 0.0012). Twenty-five of 95 patients died, 15 of 34 subjects who had developed symptoms (all liver-related deaths) and 10 of 61 who remained asymptomatic (all non-liver-related deaths) (P less than 0.001). Hepatic mortality was worse than among the normal population (P less than 0.05). A comparison of those patients developing symptoms with 111 at FH and 165 at KCH who presented with symptoms suggests no difference in survival once hepatic symptoms appear. In both centers, hepatic mortality was strongly related to symptom appearance in asymptomatic primary biliary cirrhosis: patients developing symptoms resemble those with symptoms at presentation. Other differences between the centers may reflect different referral patterns.