Mycophenolate mofetil (MMF) is the morpholinoethylester prodrug of mycophenolic acid, an agent which inhibits the proliferation of B and T lymphocytes through the noncompetitive, reversible inhibition of inosine monophosphate dehydrogenase, itself a key enzyme in the de novo synthetic pathway of guanosine nucleotides. Currently, MMF is approved for the prevention of acute renal allograft rejection when used in combination with cyclosporin and corticosteroids. Several studies have also demonstrated that this drug is useful in the treatment of refractory rejection in renal, heart and liver transplant recipients.