Deterioration of hepatic function following liver transplantation is a known complication, sometimes attributed to the use of cyclosporin A. Reaction to tacrolimus (Prograf), a relatively new and effective immunosuppressant drug, is thought to result in a much lower grade of organ dysfunction, especially in the transplanted liver. Using the ex-vivo rat model of isolated perfused liver, we evaluated hepatocellular damage and oxygen extraction when tacrolimus was administered following liver hypoperfusion. Tacrolimus did not worsen hepatic dysfunction caused by the hypoperfusion. Therefore using tacrolimus in the perioperative period might be safer than cyclosporin A, which tends to worsen hepatic damage in the presence of hypoperfusion.