There is still little information on the role of certain newly- described or reclassified organisms in disease processes and on their sites of normal carriage. Porphyromonas has seemed to be relatively non-pathogenic but recent work indicates that this is incorrect. It is clearly important in periodontal and endodontal disease and P. gingivalis is being found in extra-oral infections also. P. levii-like or PLLO and P. endodontalis-like organisms (PELO) have been recovered from clinical infections, but only in mixed culture to date. PLLO have been isolated from skin and soft tissue infections, osteomyelitis, pulmonary infection, otitis and mastoiditis, brain abscess, and bacteremia. PELO have been found in appendicitis, peritonitis, pilonidal abscess, infected decubitus ulcer, and mastoiditis and have been recovered from feces. Animal strains. notably P. macacae (including the former P. salivosa) are found in cat bite infections. Prevotella intermedia and Prevotella nigrescens have been found in extra-oral infections with equal frequency. Bilophila wadsworthia has been found in many infections, including dental and oral, pleuropulmonary, pericarditis, bacteremia, intraabdominal infection, soft tissue and bone infections, and female genital tract infections. Sutterella wadsworthensis, recently differentiated from Bacteroides gracilis, has been isolated from bacteremia, brain abscess, soft tissue and bone infection, joint fluid, and intraabdominal infections. B. gracilis (now classified as Campylobacter gracilis) is less common in infections; we have one isolate from appendicitis and all others are from above the diaphragm (brain abscess, oral and dental, neck infection, and pleural empyema; we have one case of bacteremia). Enterotoxin-producing Bacteroides fragilis has been implicated in self-limited diarrheal disease, particularly in children 1-5 years of age. Fusobacterium nucleatum has long been known as a common pathogen in anaerobic pleuropulmonary infection; recent studies found this organism in pure culture with greater frequency than was true for other organisms. Leptotrichia sanguinegens was recovered from postpartum and neonatal bacteremia. Studies of cat bite infections have revealed, in addition to Porphyromonas, Bacteroides tectum, Fusobacterium russii, Clostridium villosum and Capnocytophaga canimorsus. A study of anaerobic bacteremia by Allen et al. revealed that in recent years there has been an overall increase in recovery of Fusobacterium mortiferum, Leptotrichia buccalis, Actinomyces, Lactobacillus, and certain Clostridium species.