Allogeneic haematopoietic stem cell transplant has become first choice of treatment for many malignant and non malignant haematological disorders. Although great progress has been made to prevent and minimize transplant-associated complications, yet graft versus host disease (GVHD) remains a significant complication affecting these the outcome in these patients. It is a severe inflammatory condition that arises when recipient tissues are attacked by immune mediated donor T cells during transplantation. Acute GVHD predominately affects the skin, upper and lower GI tract, liver and occasionally the eye and oral mucosa, whereas chronic GVHD resembles more with autoimmune disorders in its clinical symptoms. These symptoms can be organ-specific or generalized throughout body.