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.