A group of 1,984 males and females (age range 13 to 84) at a military dental clinic were given oral examinations with full-mouth circumferential periodontal probing. Diagnoses were made both for individual quadrants and for the entire mouth using clearly defined diagnostic criteria. The results showed 37% of the subjects had gingivitis only, 33% had early periodontitis, 14% had moderate periodontitis, 15% had advanced periodontitis, 0.5% had juvenile periodontitis, and 0.5% had necrotizing gingivitis. The prevalence of periodontitis increased with age to a peak in the 45- to 50-year-age group. The proportion of periodontitis-affected quadrants, although initially lagging behind the overall case diagnoses, also increased with age.