Root surface caries is a specific clinical entity which has been receiving increasing attention in recent years. It has a complex, multi-factorial aetiology, but all the causal factors, and their relative contributions, are not yet clear. There appears to be a role for one or more microbiological agents, particularly in association with a diet involving frequent ingestion of fermentable sugars. Gingival recession is almost certainly a pre-requisite for the development of root surface caries, but intra-oral, site-specific differences in prevalence confuse the picture. Figures of between 20 and over 70 percent for gross prevalence have been reported, with demonstrated attack rates of between 15 and 28 percent of susceptible surfaces being affected. Difficulties in diagnosis may limit the reliability of these figures. The prevention of root surface caries is a two-phase process; the initial emphasis is on the prevention of gingival recession, and the later approach involves measures aimed at reducing the frequency of intake of known cariogenic foodstuffs, and increasing the resistance of susceptible root surfaces with topical fluoride. Medicines which can cause dry mouth must also be examined. The treatment of root surface caries involves a range of procedures, from topical fluoride to multi-surface, glass ionomer cement restorations.