Liver specific membrane lipoprotein (LSP), the target for anti-LSP antibodies in various liver diseases, is thought to be comprised of fragments of the hepatocellular plasma membrane. In the present study, therefore, evidence has been sought for the presence in LSP of the hepatocyte surface receptor (hepatic lectin) that binds desialylated glycoproteins. Eight guinea-pig anti-LSP antisera (four anti-human and four anti-rabbit LSP) were found to react by ELISA and/or RIA against affinity purified human and rabbit hepatic lectin. Binding of the antisera to 125I-hepatic lectins was inhibited by the unlabelled lectins, by human and rabbit LSP and by purified rabbit liver plasma membranes but not by a 50,000-fold excess of kidney homogenate. The results indicate that hepatic lectin is a liver specific, species cross-reactive antigen comprising about 0.25% of the protein in LSP.