This paper describes the coronal and root caries experience of subjects aged 50 years and older living in four communities in Ontario, Canada. The data were obtained as part of a comprehensive epidemiologic study of the oral health and treatment needs of this population. Caries experience was defined as the number of decayed and filled coronal and root surfaces per subject. Of 907 subjects interviewed and clinically examined, 78.3 percent were dentate and retained a mean of 18.9 teeth. The mean number of coronal decayed and filled surfaces was 23.9; 95.6 percent of subjects had at least one coronal DFS. The mean number of decayed and filled root surfaces was 3.6; 70.9 percent had at least one root DFS. The percent D/DFS was 3.5 for coronal and 20.0 for root caries. In linear regression analysis the number of teeth, making regular preventive visits, being born in Canada, and educational status emerged as predictors of coronal DFS. Predictors of root DFS were the number of surfaces with recession, the number of coronal DFS, the number of teeth, age, sex, and smoking status. These variables accounted for 42 percent and 35 percent of the variance in the number of coronal and root DFS, respectively.