__Abstract__ Since its advent 51 years ago, liver transplantation (LT) has progressed from an experimental treatment to an accepted therapeutic modality that has reversed the gloomy prognosis of end stage liver disease. The great success of LT is for the major part due to calcineurin inhibitors (CNI) like Cyclopsorin A and Tacrolimus. These are powerful immunosuppressants (IS), which prevent graft rejection and are the cornerstone of posttransplant patient management. The introduction of Cyclosporine in March 1980 marked great clinical advance for graft and patient survival. Following the introduction of cyclosporine in LT, one-year patient survival more than doubled (from approximately 33 to 68%), with an increment to above 80% ...