Although a secular decline is being seen in coronal caries in children in industrialized countries, there appears to be a relatively high prevalence of root caries, with chronologically older adults exhibiting the highest prevalences. This paper reviews the descriptive and analytical epidemiology of root caries as found in recent national, regional, and local studies. A review of the variety of study designs, populations surveyed, and epidemiologic criteria for root caries comprising recent studies is presented as a background for comparison of prevalence rates which range from 7.3% to 69.7% of the population with root decay. In the few incidence studies reported, attack rates range from 1.6 surfaces per 100 surfaces at risk to 6.3 per 1000 surface-months at risk. Risk indicators for root caries are also reviewed with studies applying multivariate techniques implicating age, fluoride, educational level, use of dental services, coronal caries, loss of attachment, and number of teeth as possible risk factors. Although incidence studies have isolated risk factors, the small number of studies result in little agreement. Risk factor models from the Iowa 65+ Oral Health Study and a Risk Indicator model from the Piedmont 65+ Dental Study are presented to illustrate the variety of factors that may be involved in the expression of root surface caries in human populations.