The ability of a purified rabbit liver membrane protein that selectively binds desialylated glycoproteins to induce desialylated human peripheral blood lymphocytes to mediate mitogen-induced cellular cytotoxicity has been determined. After short term exposure to purified hepatic binding protein, desialylated, but not intact, lymphocytes exhibited mitogen-induced cellular cytotoxicity against Chang target cells, which do not have exposed hepatic binding protein on their surface membrane. Furthermore, desialylated lymphocytes, in the absence of purified hepatic binding protein, reduced the proportion of isolated rabbit hepatocytes that adhered to plastic to a significantly greater extent than did intact lymphocytes, suggesting that the exposed hepatic binding protein demonstrated on the surface membrane of these target cells is capable of inducing mitogen-induced cellular cytotoxicity. The specific inhibition of this effect by asialo-orosomucoid, but not by intact orosomucoid, indicates that the site involved in the binding of asialo-glycoproteins to hepatic binding protein is probably also responsible for the induction of mitogen-induced cellular cytoxocity. The demonstration that hepatic binding protein, a normal constituent of the surface, membrane of mammalian hepatocytes, can induce mitogen-induced cellular cytotoxicity, suggests that mitogen-induced cellular cytotoxicity may be a mechanism of cellular injury in vivo.