Serial estimations of serum alpha-fetoprotein in 130 white patients from the United Kingdom with primary biliary cirrhosis who were followed for periods of 1-52 mo revealed 5 cases of hepatocellular carcinoma; all were subsequently confirmed histologically. At the time alpha-fetoprotein was first noted to be elevated, none had signs or symptoms of tumor development. Of the 52 patients who died during the follow-up period, hepatocellular carcinoma was the cause of death in 3 (33%) of the 9 men, and 2 (5%) of the 43 women. Allowing for the marked predominance of women among patients with primary biliary cirrhosis, hepatocellular carcinoma may be no less frequent in primary biliary cirrhosis than in other types of cirrhosis.