Mycophenolic acid inhibits an enzyme, inosine monophosphate dehydrogenase (IMPDH), blocking purine synthesis of lymphocytes and therefore functioning as an effective immunosuppressive agent in transplantation. Currently, there are two available forms of mycophenolic acid (MPA) available; mycophenolate mofetil (MMF) and enteric-coated, delayed-release mycophenolate sodium (EC-MPS). Both products are approved for prophylaxis of organ rejection in renal transplant recipients. The use of MPA may be associated with adverse gastrointestinal effects which can lead to a reduction of the dose or discontinuation of therapy. Enteric-coated MPS was developed to reduce the upper gastrointestinal side effects due to its delayed release in the small intestines. Similar systemic MPA exposure is provided by oral administration of MMF 1000 mg daily and EC-MPS 720 mg, which contain near equimolar MPA content. Clinical trials in renal transplant recipients have demonstrated that EC-MPS is therapeutically equivalent to MMF when used at the time of transplantation and when used for conversion for gastrointestinal complications. The available literature regarding the incidence and severity of gastrointestinal adverse effects and the impact on quality of life remains controversial. Prospective, randomized trials of the available MPA formulations are warranted to further explore the gastrointestinal adverse effect profiles.