A sample of 729 noninstitutionalized, dentulous, adult males has been followed for 10 years, with a series of 4 comprehensive oral and radiographic examinations carried out under standard conditions at intervals of about 3 years. Individual counts of new decayed and filled surfaces (DFS) occurring during the intervals between examinations and sound surfaces at risk have been determined in order to calculate mean DFS rates per 100 surfaces at risk adjusted to a period of 1 year. The range of observed mean, annual rates is 1.03–1.92, with a mean annual rate of 1.36 new DFS per 100 surfaces at risk. Due to the difficulty in identifying secondary caries, the above rates provide an underestimate of the actual values. However, those rates observed for adults fall within the range of rates calculated according to the same formula for children 7–12 years of age. This demonstrates that caries attack rates may be similar in children and adu