The purpose of this study is to replace the mycophenolate mofetil (Cellcept) which is our usual therapy after liver transplantation with sodium mycophenolic acid (Myfortic®) and to find out the effect this change may have on the development of side effects such as relief of gastrointestinal (stomach) problems. In the past we have had to stop Cellcept (our current drug) because of these side effects. We will also try to see if improved usage of this drug (Myfortic®) will allow us to use lower doses of other medications that lower your immune system. We will do some special tests on your blood to see if the amount of the drug is related with its effect on the immune system and side effects. Both Cellcept and Myfortic® are FDA approved medications although Myfortic® is not approved for use after liver transplantation. Myfortic® is really the same active drug as Cellcept® (Mycophenolic acid) but has been coated to prevent breakdown of the drug in the stomach and is made to lower the known gastrointestinal effects of Cellcept such as diarrhea, abdominal pain and nausea.