Previous studies have demonstrated the efficacy of syngeneic hepatocyte transplantation in the treatment of D-galactosamine-induced acute hepatic failure in Lewis strain rats. This report describes the efficacy and immunological consequences of allogeneic and xenogeneic hepatocyte transplantation in the same model. The i.p. administration of allogeneic (minor and major histoincompatibility) hepatocytes or xenogeneic (rabbit or porcine) hepatocytes at a dose of 4 x 10(7) cells/rat given at 48 hr after toxin all resulted in significant improvement in survival compared to that of controls, and also comparable to the results obtained with syngeneic hepatocyte transplantation. Sensitization to i.p. allogeneic (WF) hepatocyte administration was demonstrated by in vivo 51Cr release, indirect immunofluorescent technique, and accelerated skin allograft rejection. Similarly, the in vivo 51Cr release assay was able to detect sensitization to porcine hepatocytes. Despite evidence of immunogenicity, redosing with either WF or porcine hepatocytes resulted in no overt toxicity. Furthermore, presensitization by either WF hepatocytes or skin allografts did not adversely affect survival after WF hepatocyte treatment in D-galactosamine-induced hepatic failure in Lewis strain rats. These data demonstrate that histocompatibility is not a constraint to successful hepatocyte transplantation and that repeated treatments are potentially safe and efficacious despite sensitization.