The transplantation of donor organs into patients with end stage organ disease is a lifesaving procedure. However, transplanted organs may develop pathology that results in graft dysfunction in the post-transplant period. This pathology may include rejection (acute or chronic), infection (reactivation or new), reoccurrence of the original disease, newly developed disease (de novo), medication toxicity, or possibly malignancy. A biopsy of the transplanted organ provides valuable information regarding the responsible pathology and assists the clinician with management decisions. Responsibilities for the interpretation of tranpslant biopsies in the various organ systems are shared by a group of experienced pathologists in the Department of Pathology and Laboratory Medicine.