An equol-producing bacterium, strain DZE(T), which was isolated from human faeces, was characterized by morphological, biochemical and molecular methods. The isolate was Gram-positive, obligately anaerobic, non-spore-forming, asaccharolytic and rod-shaped. 16S rRNA gene sequence analysis showed 92.8, 91.0, 91.1 and 90.6% similarities with Slackia faecicanis, Slackia exigua, Slackia heliotrinireducens and Slackia isoflavoniconvertens, respectively. Based on these data, we propose a novel species of the genus Slackia, Slackia equolifaciens sp. nov. The major cellular fatty acids are C14:0, C18:1omega9c and C18:1omega9c DMA (dimethyl acetal). The DNA G+C content of the strain is 60.8 mol%. The type strain of S. equolifaciens sp. nov. is DZET (=JCM 16059T =CCUG 58231T).