Dental caries experience in primary teeth is descr. through a full cycle from eruption to exfoliation. Dental examinations of 3009 Illinois children aged 1-71 mos., furnish the data for the 1st part of the curve; longitudinal data on 233 Cleveland school children, through the age ranges 60-156 mos., make up the 2d part of the curve. The examination findings in each of the 20 tooth spaces for all children were analyzed for sound, decayed, missing and indicated for extraction, filled, and total dental caries experience. Rates are given for each of these components. Although there are differences in attack rates between the 2 groups of children, the general nature of the curves for dental caries experience is consistent. The data suggest that dental caries attack in primary teeth follows the pattern found in permanent teeth, in that attack lags behind eruption but rises as posteruptive tooth age increases. Also evident is the inverse relation between the amt. of filled teeth and tooth mortality.