Chronic rhinosinusitis (CRS) is an inflammatory disorder of the nasal cavity and paranasal sinus related to bacterial infection. A previous study suggested that a sp.cific bacterial group may have an important role in the course of CRS. In this study, bacteria isolated from CRS patients were characterized. A total of 15 strains were identified as Gram-positive anaerobic cocci (GPAC), which were able to utilize peptone as a sole carbon source. Sequencing of the 16S ribosomal RNA gene revealed that the isolates were closely related to members of the genus Peptoniphilus (>97% similarity) within the Clostridiales Family XI. Incertae Sedis. Genotypic and phenotypic characterization suggests that these isolates represent a nov.l sp.cies of the genus Peptoniphilus associated with CRS. The type strain of Peptoniphilus rhinitidis is 1-13T (=KCTC 5985T=JCM 17448T).