Two calves coming from different herds showed at post-mortem examination a fibrinous enteritis with mucosal necrosis particularly in the ileal-colonic tract. Histologically, amphophilic intranuclear inclusion bodies were the main feature. They were located in the endothelial cells of the intestine and mesenteric lymph cells. Ultramicroscopic examination of the inclusion bodies revealed the presence of an adenovirus. In one case the virus was isolated on cell cultures and further classified as bovine adenovirus type 4.