The presentation or method of detection of 93 patients with primary biliary cirrhosis (PBC) from Northern England is reported. Almost half (45/93) the patients had no symptoms of liver disease when PBC was diagnosed; in many of them serum antimitochondrial activity (AMA) was detected during immunological screening for other diseases. 13 patients with normal liver function tests had symptomless PBC. Liver histology in 6 of these was diagnostic for PBC, and 7 had histology suggestive of PBC; all had a positive AMA titre greater than or equal to 1/40. The mortality of the symptom-free AMA-positive patients over a mean follow-up of 4-5 years did not differ from that of the general population. Only 1 out of 45 initially symptom-free patients died in the follow-up period (8 months-12 years). 37 patients had disorders which may be associated with PBC--including 16 with thyroid disease, 9 with rheumatoid arthritis, and 5 with mixed connective tissue disease. It is suggest that, as with autoimmune thyroid disease, overt organ damage never develops in many patients with symptomless PBC.