It was suggested that 3 strains of bovine viral diarrhea virus (BVDV) isolated from persistently infected calves in Tochigi prefecture in Japan belonged to BVDV type II. It was recognized lack of PstI site on the 5'-untranslated region of genome of them as well as BVDV type II reported previously. Inoculated with the 3 strains, the calves showed the mild decrease of platelet counts which was specific clinical sign of BVDV type II. We should report that the 3 strains were the first BVDV type II isolated in Japan. Neutralizing antibody titers of the antisera against the 3 strains using laboratory strains as neutralizing virus were lower than those of them using homologous strains. Therefore, it was indicated that the difference between BVDV type I and BVDV type II in the antigenicity.