There are two processes that cause diarrhea as the clinical manifestation of graft versus host disease. The first is the obvious immunologic attack on the colonic epithelium of the recipient. Once this immunologic attack has been abated the recipient is left with a colonic mucosa that is devoid of microvilli and has a smooth intestinal boarder. This is frequently subject to superinfections from bacteria all of which cause the diarrhea to continue. Researchers only endpoint to measure clinical response of immunosuppression is the resolution of diarrhea. The human recombinant keratinocyte growth factor stimulates the growth of colonic epithelium. The growth of colonic epithelium will in turn probably ameliorate some of the diarrhea associated with graft versus host disease.