Graft versus host disease (GVHD) is one of the most common complications of bone marrow transplantation (BMT). Targets of GVHD are the gastro-intestinal tract (GIT) liver and skin, causing severe diarrhea and mucosal aberration and hepatitis that can cause life threatening liver failure. As a result of the mucosal aberration and the general immuno-suppression, caused both by the GVHD process itself and by the anti GVHD therapy, these patients are highly susceptible for severe, life threatening infections that usually originate from the GIT. Systemic steroids are the backbone of anti GVHD therapy. However, in GVHD systemic steroids have to be administered for a prolonged duration and in high doses, thus causing prolonged immune suppression, and exposing the patients to steroid side effects such as hypertension, diabetes, cataract formation etc.