The liver is one of the main target organs of Marburg virus (MBG), a filovirus causing severe haemorrhagic fever with a high fatality rate in humans and non-human primates. MBG grown in certain cells does not contain neuraminic acid, but has terminal galactose on its surface glycoprotein. This observation indicated that the asialoglycoprotein receptor (ASGP-R) of hepatocytes may serve as a receptor for MBG in the liver. Binding studies revealed that the attachment of MBG to ASGP-R-expressing HepG2 cells, but not to ASGP-R-negative E6 Vero cells, has the characteristics of ligand binding to the ASGP-R: binding is dependent on calcium and is inhibited by excess asialofetuin and by anti-ASGP-R antiserum. Asialofetuin and the specific antiserum also inhibited MBG infection of HepG2 cells. In addition, it was shown that expression of ASGP-R cDNA in NIH 3T3 cells enhanced the susceptibility of these cells to MBG infection 4·5-fold. Interaction of MBG with the hepatic ASGP-R could thus explain the marked hepatotropism of the virus.