This is an open-labeled, prospective, non-randomized pilot-phase study of the enteric-coated, Myfortic® versus the non enteric-coated, Cellcept® in patients who are within 5 years of having undergone heart transplant surgery who are currently taking Cellcept®. After the initial screening, 20 patients who fulfill the inclusion criteria and report symptoms of gastrointestinal side-effects while taking Cellcept will be switched to Myfortic. All 20 patients will be followed closely over a period of 6 months following enrollment. Concomitant immunosuppressive therapy will continue in all patients per standard treatment protocol.