Five patients underwent bone-marrow transplantation, and graft-vs.-host disease (GVHD) developed. Radiographic features are described. Three patients showed an abrupt transition at the jejuno-ileal junction from normal small bowel to ileal loops which were narrowed, tubular, separated, edematous, and, generally, without mucosal markings. The transit time for the contrast material to reach the anus from the mouth was 20 to 25 minutes. A fourth patient showed mucosal ulcerations of the transverse and descending colon. The fifth patient with acute, ultimately fatal GVHD had an edematous duodenum and colon, in addition to an edematous, tubular jejunum and ileum without mucosal markings. Transit time through the intestines for the contrast material was rapid.