Dialister pneumosintes is a nonfermentative, gram-negative anaerobic rod which is considered as a commensal organism of the oral cavity. A 77-year-old man with a history of aortic stenosis was visited to ER for dyspnea and fever. D. pneumosintes and Streptococcus anginosus were isolated from blood culture, and also D. pneumosintes was identified by 16S rRNA-based gene sequencing. This case report is the first case of isolation of D. pneumosintes from blood in Korea, and highlights the usefulness of DNA sequencing to identify pathogens in organism which is difficult to identify by biochemical identification method. (Ann Clin Microbiol 2015;18:60-63)