Hepatic copper content, measured by neutron activation analysis, has been studied in 70 patients during a median observation period of 3 years. In 15 patients with chronic active hepatitis the median hepatic copper content was 39 micrograms/g dry weight at the start and 28 micrograms/g dry weight at the end of the observation period, during which the clinical condition was improved in most patients. The hepatic copper content did not change significantly (41 versus 54 micrograms/g dry weight) in 28 patients with hepatobiliary disorders associated with inflammatory bowel disease. In 27 patients with primary biliary cirrhosis the median hepatic copper concentration was initially 176 micrograms/g dry weight, and at the follow up 186 micrograms/g dry weight. Serum ceruloplasmin was elevated in most of the patients with hepatobiliary disorders associated with inflammatory bowel disease and in all the patients with primary biliary cirrhosis and remained at high levels throughout the observation period. In primary biliary cirrhosis the hepatic copper content was correlated with bilirubin and alkaline phosphatases but not with ceruloplasmin, coagulation factors, or aminotransferases. Ceruloplasmin was not significantly correlated with other "liver tests". We conclude that the hepatic copper content and serum ceruloplasmin were remarkably constant during 3 years of observation in various liver disorders. Our study gave no evidence of a hepatotoxic effect of copper, since no relation between the initial hepatic copper concentration and the clinical course could be detected.