The authors report the case of a 41-year-old woman who developed an acute graft-versus-host disease following bone marrow transplantation for post-polycythemic myeloid metaplasia; liver, cutaneous and intestinal lesions were present, associated with a severe protein-losing enteropathy. Symptoms, diagnostic procedures and therapy of intestinal graft-versus-host disease are reviewed. The intestinal clearance of alpha-1 antitrypsin was particularly useful to assess the response to medial treatment, which induced a complete remission.