Livers from human foetuses obtained from terminations of pregnancy by suction were used to establish long-term cultures of hepatocytes. Functional activities of the hepatocellular population in these cultures were monitored by immunoperoxidase staining during and up to the 90 days' life of the cultures. Intracellular localization of albumin and alpha-foetoprotien in cultures of the same age and from the same specimen indicate that syntheses of these two markers in foetal hepatocytes occur simultaneously. No qualitative differences were observed in the biosynthetic capacity of the cells maintained in tissue culture medium with and without serum. Fibroblast-like cells seen in the almost homogeneous population of hepatocytes did not stain for albumin and alpha-foetoprotein.