Biochemical, molecular chemical and molecular genetic studies were performed on an unknown gram-positive, catalase-negative, coccus-shaped organism isolated from the intestine of a cow affected with catarrhal enteritis. The organism was tentatively identified as a streptococcal species based on results of cellular morphological and biochemical tests. 16S rRNA gene sequencing studies confirmed its provisional identification as a member of the genus Streptococcus, but the organism did not correspond to any recognized species of this genus. The nearest phylogenetic relatives of the unknown coccus from a calf were Streptococcus acidominimus and Streptococcus suis. The unknown bacterium, however, was distinguished from these species and other animal streptococci by biochemical tests and electrophoretic analysis of whole-cell proteins. Based on both phenotypic and phylogenetic findings, it is proposed that the unknown bacterium be classified as a novel species of the genus Streptococcus, Streptococcus entericus sp. nov. The type strain is CECT 5353T (= CCUG 44616T).