Characteristics of the hemadsorbing enteric (HADEN) virus were studied in bovine embryonic kidney (BEK) cell cultures. The virus was found to be resistant to both ethyl ether and sodium desoxycbolate. The growth of the virus was not inhibited by 5-iodo-2′-deoxyuridine, but guanidine hydrochloride completely inhibited its multiplication. Virus infectivity was not affected by heating at 56 C for 4 hours. No loss in titer occurred after a 30-minute exposure to pH 2.0; however, very little infective virus remained after a 2-hour exposure to this acidity. Of nine cell culture systems tested, HADEN virus produced cytopathic changes only in BEK and bovine lymph node cultures. Cytological studies on infected cells were conducted using fluorescent antibody, acridine orange, and inclusion body staining techniques. The fluorescent antibody staining first revealed viral antigen in the cytoplasm (6 hours) followed by nuclear invasion, which was pronounced by 48 hours. Acridine orange staining showed an increase in cytoplasmic ribonucleic acid staining 72 hours postinfection. The virus produced type A intranuclear inclusions which were fully formed by 72 hours. Electron micrographs of negatively stained virus preparations showed spherical particles approximately 28 mμ in diameter with a capsomeric structure. It is suggested that HADEN virus is a member of the bovine enterovirus group.