The aim of this study was to compare the complete avoidance of calcineurin inhibitors (CI) using a sirolimus-based immunosuppressive regimen to a tacrolimus-based regimen in kidney transplantation. This study was a prospective open-label trial randomizing patients to receive tacrolimus, mycophenolate mofetil and prednisone or sirolimus, mycophenolate mofetil and prednisone. All patients received antithymocyte globulin induction. All rejection episodes were proven by biopsy. The hypothesis was that CI free immunosuppression after kidney transplantation will lead to an increase in glomerular filtration rate (GFR) at one year after kidney transplantation.