Liposomal FK506 is a new formulation of FK506 that increases FK506 levels in the liver and decreases them in the kidney in comparison to conventional IV formulation. In the present study, the efficacy of liposomal FK506 was evaluated in canine kidney and liver transplantation models. Liposomal FK506 increased the immunosuppressive efficacy of FK506 in the liver transplantation model, but decreased it in the kidney transplantation model. These results suggest that local immunosuppressive effects with increased intragraft FK506 level would play an important role in enhancing the immunosuppressive efficacy of liposomal FK506 in liver transplantation.