This paper reports on the performance of galactosylated polyethersulphone (PES) membrane bioreactor that enables the long-term maintenance of liver-specific functions of human hepatocytes under continuous perfusion. Galactose derivate was immobilized on PES membranes modified by plasma deposited acrylic acid coating. Galactosylated membranes had specific interactions with hepatocytes because of binding between the galactose moiety and the asyaloglycoprotein receptor present on the hepatocyte cytoplasmatic membrane. The liver-specific functions of human hepatocytes cultured in the galactosylated membrane bioreactor were explored with respect to urea synthesis, albumin production and secretion of total proteins. The liver-specific functions of human hepatocytes cultured in the galactosylated membrane bioreactor were explored with respect to urea synthesis, albumin production and secretion of total proteins. Human hepatocytes were cultured in the membrane bioreactor under continuous perfusion for 21 days. Morphological examinations of hepatocytes in the bioreactor showed that cells developed aggregation and formed tight junctions. Vinculin was distributed into the cytoplasm and focal adhesions were visible. Human hepatocytes maintained their liver-specific functions for the whole culture time in terms of urea synthesis and albumin production as well as protein secretion. The gene expression of albumin and C-reactive proteins confirmed the maintenance at the gene level of the specific functions of cells in the bioreactor. This study demonstrated that the galactosylated membrane bioreactor is able to support extended in vitro hepatocyte functions. (c) 2007 Elsevier B.V. All rights reserved.