Studies of a few last years give evidence for a role of apoptosis not only in graft rejection but also in induction of transplantation tolerance. Apoptosis – programmed cell death is an active process which refers to superflous and defective cells. For a responsiveness to allograft the most important are two mechanisms of apoptosis: AICD (activation induced cell death) which involves Fas/FasL engage- ment and PCD (passive cell death) – caused by cytokine withdrawal. Graft rejection is caused by genetic differences between a donor and a recipient.