Infrared spectrometric analysis and thin-layer chromatography were employed to detect sphingolipids in the genus Bacteroides species. Sphingolipids were found in the bacteria belonging to B. fragilis, B. melaninogenicus, B. oralis, and B. ruminicola, but not in B. succinogenes, B. furcosus, B. hypermegas, B. amylophilus, and B. multiacidus. The taxonomical position of the bacteria that contain no sphingolipids has come into the question.