Liver induced tolerance and the protecting effect towards a co-transplanted organ are well known effects after liver transplantation in rats. Isolated liver transplantation and combined liver/small bowel transplantation are used to investigate the cellular mechanisms of those two phenomenons. In both transplantation models a transient rejection process can be observed. During this response recipient derived graft infiltrating T-cells are subsequently inactivated. The initial peak of apoptotic cell death in the liver lobuli decreases and is followed by an increase in apoptosis of the infiltrating T-cells during the end of the rejection response. Donor specific tolerance occurs after LTx and LDDTx respectively, proofed by indicator heart transplantation.