All 9-10-year-old children in one Finnish county were screened with a standardized set of tasks for their mental performance. 58 verified mentally retarded and 58 randomly selected healthy children were examined for dental and gingival status and level of oral hygiene. Comparisons were made between the retarded and the healthy, as well as between subgroups of the retarded. Similar DFS-values, higher DS-values and an inferior level of oral hygiene in terms of VPI were found in mentally retarded when compared with healthy children. No evident difference was found in gingival status (by GBI) between the retarded and the healthy. The mildly or moderately retarded found by the screening and not yet included in special welfare had the highest DFS-scores, the highest prevalence of untreated caries and the poorest gingival health among the retarded.