Three virus strains were isolated in DK cell cultures inoculated with fecal specimens of dogs manifesting diarrhea. The isolates were identified as reoviruses on the basis of their biological and physico- chemical properities. They possessed reovirus type 3 antigenic specificity revealed by hemagglutination-inhibition and neutrarization tests with the reovirus prototype strains. It was suspected that the isolates were participated in this diarrheic cases.