SummaryThree strains of a small, hemagglutinating DNA virus were isolated from the feces of calves and identified as bovine parvovirus type 1 (HADEN). The virus readily multiplied with cytopathie effect and produced eosinophilic intranuclear inclusion bodies in bovine kidney cell cultures. The virus agglutinated ery~hrocytes of horse, sheep, goat, guinea pig, hamster, duck, goose and human, but not those of mouse, rabbit, chicken and cattle. The growth of the virus was inhibited by 5-iodo-2'-deoxyuridine. The virus showed a high degree of acid-and heat-stability, and resistance to ether, chloroform, sodium deo~ycholate, and trypsin, and was not affected by incubation at 50 ~ C for 60 minutes in the presence of 1 M MgC12. The virus passed through membrane filters of 50 nm pore size. The buoyant density of the virion was estimated at 1.38 g/ml in CsC] density gradient.