It is generally known that the degree of periodontal breakdown increases with increasing age. The extent to which aging of periodontal tissues plays a part in this respect poses a question which is yet to be answered. Aging proves to be accompanied by a variety of periodontal changes. The periodontal tissues themselves show evidence of aging, there are indications that the composition of the plaque changes, and the reaction of the periodontium to the presence of plaque probably changes as well. There is as yet no sufficient evidence of a physiological apical migration of the epithelial attachment in human subjects. It seems plausible that periodontal breakdown can occur only in the presence of plaque with consequent inflammation of the periodontium, or as a result of trauma. Whether changes in plaque composition with age exert any influence on the course of periodontal breakdown is uncertain: the data available are not yet sufficient to warrant definite conclusions. The same applies to the influence which a changing reaction of the periodontium to the presence of plaque may have on the course of periodontal breakdown. Research findings do suggest that the degree of periodontal breakdown increases with age, that with increasing age inflammation of the periodontium tends to develop more rapidly and that in the process of aging the periodontium shows a slower rate of wound healing. However, these phenomena are overshadowed by the patients' susceptibility to periodontal disease. This implies that (1) the susceptibility to periodontal disease is more significant for the rate of periodontal destruction than the length of time plaque is present (the age effect) and (2) the greater the susceptibility to periodontal disease, the slower the rate of wound healing and the more rapidly inflammation of the periodontium tends to develop.