The Odocoileus hemionus deer adenovirus (OdAdV-1) causes systemic and local vasculitis and proves extremely lethal for mule deer. To characterize the virus, part of the genome flanking the fiber gene was cloned and sequenced. The sequence revealed two open-reading frames that mapped to pVIII hexon-associated protein precursor and fiber protein of several other adenoviruses. The highest amino acid homology for pVIII and fiber was found with the members of the proposed Atadenovirus genus: ovine adenovirus isolate 287 (OAdV-287), bovine adenovirus 4 (BAdV-4) and duck adenovirus 1 (DAdV-1). The homology with bovine adenovirus type 3 (BAdV-3) proved low. The E3 region was not found between the gene for pVIII and fiber. These data suggest that OdAdV-1 is a member of the Atadenovirus genus.