The effect of ursodeoxycholic acid treatment on survival in primary biliary cirrhosis was studied in 40 patients with symptomatic disease. Two patients developed early exacerbation of symptoms and stopped therapy in days; they are both alive 4 and 4 1/2 years later. The other 38 patients have continued on treatment for up to 10 years. Results were compared with 12 other similar cases previously seen but not given specific therapy. Kaplan-Meier analysis showed that ursodeoxycholic acid treatment was associated with better survival (p < 0.05) after the first two years of therapy. Predictors of favourable outcome included histological stage I disease. In 26 patients with primary biliary cirrhosis stage II, III or IV, therapy showed a trend to improved survival, but this was still significantly worse than the general population. Prognosis was not different between these different advanced stages. Symptoms improved in 28 out of 40 patients on ursodeoxycholic acid, but 50% had a recurrence by two years.