Pigs usually reject MHC incompatible liver allografts less aggressively than skin or kidney allografts. Orthotopic liver allografts can survive undefinitely without any immunosuppression. The liver is considered to be an immunologically privileged organ. Despite this phenomenon, morphological changes and deranged liver function due to rejection reaction are regularly seen; their intensity depends on the histocompatibility antigen disparity between donor and recipient. In long-term survivors the continuous exposure of the recipient's immune system to the liver allograft results in an increasing fibrosis which can turn into liver cirrhosis being considered as the result of chronic rejection. The cholestasis represents a remarkable feature, which is mainly due to perfusion, infection and immunological reaction.