In a prospective series of 205 patients undergoing liver biopsy, fasting plasma total bile acid (TBA) levels were compared with 11 different histological features. The TBA level was found to correlate positively (P less than 0.001) with the extent of total hepatic damage. In both alcoholic (no. = 93) and non-alcoholic disease (no. = 112) TBA levels correlated better with characteristics consistent with inflammation and Kupffer cell activity than with connective tissue changes. The degree of steatosis had no effect on TBA levels. Of 117 patients with greater than or equal to 5 of 33 possible biopsy score points, 44, or 38%, had normal TBA levels. All patients with biopsy scores greater than or equal to 12 had abnormally high TBA. Although an elevated fasting TBA level is specific for hepatobiliary disease, the test is insensitive and is not appropriate for screening purposes. This applies equally to alcoholic and non-alcoholic liver disease.