In a retrospective study we investigated the risk of acute rejection after the withdrawal of mycophenolate mofetil (MMF) in 39 adult patients treated with cyclosporine (CyA), prednisone, and MMF for at least 6 months following renal transplantation. After reaching a stable renal graft function, MMF was withdrawn and CyA and prednisone were continued. Preceding the withdrawal of MMF, four patients experienced an acute rejection. During a median follow-up of 38 months after discontinuing MMF, no acute rejection occurred. The mean serum creatinine level did not change during the first 6 months after withdrawal of MMF. We conclude that elective withdrawal of MMF in stable renal transplant recipients at 6 months after transplantation bears no important risk of an occurrence of acute rejection.