Osteomyelitis of the pubic bone due to anaerobic bacteria has been reported infrequently, although an entity known as "sterile" osteitis pubis is common to the literature. We have described two cases of pubic osteomyelitis due to anaerobic bacteria, discussed two previously reported cases, and suggested that most cases of what has previously been termed sterile osteitis pubis may actually have been due to anaerobic bacteria that were not isolated because of deficiencies in collection, transport, and culture of clinical specimens. Included are the pathogenesis and an approach to the treatment of this entity.