Human autopsy specimens bearing posterior teeth with interproximal areas were studied by quantifying various histological parameters. Osteoclasts were found to be equally frequent on the crestal, alveolar wall and endosteal alveolar bone surfaces. Evidence of previous resorption in the form of scalloping suggested that osteoclastic activity had also occurred in the past. The size of the inflammatory infiltrate was significantly correlated with the degree of bone loss, but not with the number of osteoclasts. However, the distance from the apical border of the inflammatory infiltrate to the alveolar bone crest was significantly correlated with both the number of osteoclasts on the alveolar crest, as well as their total number. These findings in the human periodontitis lesion support those from the animal model system which have indicated that the proximity of the inflammatory infiltrate to the bone surface is a significant factor in the osteoclastic resorption of alveolar bone.