The 3 cases suffering from asymptomatic primary biliary cirrhosis (aPBC) were all older than 70 and female. Case 1, 2 and 3 were respectively 77, 72 and 70 years old. The final diagnosis was made on the basis of clinical observation and liver biopsy. Case 1 was diagnosed as CAH-PBC mixed type from histological findings and classified as stage II-III according to Scheuer's classification. Case 2 was stage I and exhibited morphological features of PBC with arteriosclerotic change. Case 3 was stage I and had dysplasia-like large nuclei in some hepatic cells. Clinically, all cases were AMA positive. Elevation of serum ALP and IgM values was recognized in 2 cases, but serum transaminase and ALP values were not elevated in Case 2 for 1 year. In the follow-up observation during 5 years. Case 1 remained asymptomatic except for gradual elevation of serum ALP value. AMA, which was positive at the time of diagnosis, is now negative after 5 years, but now produces high potency ANA. The incidence of PBC in those aged older than 70 in Japan accounts for only 2-3% of all PBC cases. According to some reports, the prognosis of PBC deteriorates with age. In 3 cases reported here, however, the clinical course did not deteriorate even in untreated cases. This suggests the possibility that some aPBC cases diagnosed at an age older than 70 may have a favorable prognosis.