The value of serum bile acid concentrations for predicting prognosis in cirrhotics was compared with the prognostic significance of clinical and laboratory findings in a prospective 1-year study of 76 patients with cirrhosis. A commercial radioimmunoassay for total serum-conjugated primary bile acids was used. Of 76 patients, 16 died within the follow-up period. The concentration of bile acids in serum more closely correlated with mortality in cirrhosis than the commonly used clinical and laboratory parameters such as the Number Connection Test, ascites, albumin, pseudocholinesterase, bilirubin, prothrombin time and nutritional state. Serum bile acids alone yielded a prediction of mortality comparable to the Child classification. When logistic regression analysis was performed, optimal prediction of prognosis was achieved with the combination of serum bile acids and the Number Connection Test. Serum bile acid levels alone or in combination with the Number Connection Test may be a clinically useful prognostic index in cirrhosis.