Background: Graft-versus-host disease (GVHD) frequently produces cutaneous and systemic complications in patients receiving allogenic bone marrow transplantation. Familiarity with these reactions and their treatment is important to dermatologists involved in the care of bone marrow transplant recipients. Objective: Our purpose was to find the clinical and histopathological features of cutaneous graft versus host reaction (GVHR). Methods: We retrospectively reviewed patients who had undergone cutaneous GVHR after allogenic bone marrow transplantation in our institute over ten years. Results and Conclusion: 1. We found GVHD in 40% patients with allogenic bone marrow transplantation. 2. There was cutaneous GVHR in 86.5%, liver GVHR in 44.2% and gastrointestinal systems involvement in 34.6% of all GVHD patients. 3. Acute cutaneous GVHR presented as a generalized maculopapular exanthem and chronic cutaneous GVHR appeared as generalized maculopapular eruptions or lichenoid lesions. 4. Histopathologically, in 65.4%(17/26) of acute GVHR showed characteristic changes such as basal cell degeneration, dyskeratotic cells in epidermis, spongiosis, subepidermal cleft, and inflammatory cell infiltration and in 78.3% of chronic GVHR revealed acute GVHR-like or lichenoid change. 5. Treatment of moderate to severe GVHD consisted of high-dose corticosteroids and cyclosporine. There were 23.1% mortality due to sepsis in GVHD patients. (Korean J Dermatol 2001; 39(3): 267-273)