The oral health of 219 residents with mental retardation living in a long-term-care institution near Milan was assessed. The dental and periodontal status, daily habits, oral hygiene, and oral mucosal status were evaluated. Of the sample, 179 (81.7%) were males. The mean age of the residents was 61.3 years, and the degree of cooperation was evaluated as good for 131 subjects (59.8%), fair for 79 (36.1%), and poor for nine (4.1%). The percentage of residents who were edentulous was 21.5% (47 subjects), of whom 28 subjects (59.6%) were without dentures. Evaluation showed an overall DMFT of 23.1, and the average number of missing teeth was 20.5. All subjects had periodontal disease: Forty-five subjects had calculus and/or shallow pockets (4-5 mm); 61 had deep pockets (> or = 6 mm). The most common mucosal lesion was oral stomatitis (49.3%). These findings underline the need for special programs aimed at institutionalized subjects with mental retardation.