OBJECTIVE: To evaluate the relationship between oral health status and nutritional deficiency. DESIGN: Cross-sectional clinical study. SUBJECTS: 324 institutionalized frail older adults (mean age 85). MEASUREMENTS: Structured oral examination including an evaluation of mucosa, periodontal state, caries prevalence and denture quality. The nutritional status was assessed using serum albumin concentration and the body mass index. Physical dependence was assessed using the Barthel index. To identify oral health disorders associated with markers of malnutrition we performed the Pearson chi2 test separately for edentulous and dentate patients. Subjects with at least one of the identified oral disorders were classified as having compromised oral functional status. RESULTS: About two-thirds of the subjects were functionally dependent and half had either a body mass index < 21 kg/m2 or serum albumin < 33 g/l. Among the edentulous, wearing dentures with defective bases or not wearing dentures at all were the factors most associated with malnutrition. In dentate subjects, corresponding identifiers were the number of occluding pairs of teeth (five or fewer, either natural or prosthetic), the number of retained roots (four or more), and the presence of mobile teeth. According to these criteria, 31% of the subjects had a compromised oral functional status. This was more frequently found in dependent subjects (37%) than semi-dependent subjects (18%; odds ratio, 2.6; 95% confidence interval, 1.4-4.8). Those with compromised oral functional status had a significantly lower body mass index and serum albumin concentration. {CONCLUSION}: Specific detrimental oral conditions are associated with nutritional deficiency in very old people.