The prevalence of objective signs and subjectively perceived symptoms of mandibular dysfunction were studied in a sample comprising 1600 subjects, 400 each aged 25, 35, 50 and 65 years. Eighty per cent of the subjects were examined clinically. The prevalence figures were higher among the females than among the males, and a slight tendency for higher frequencies of clinical signs was observed with increasing age. In view of the severity of clinical signs preference should be given for a total of 27% of the subjects when considering the need of treatment. The number of remaining teeth in subjects with natural teeth and no additional removable dentures had no marked influence on the prevalence of mandibular dysfunction, but subjects with complete dentures had signs and symptoms of dysfunction more often than those with natural dentition. The sex and age differences can partly be explained by the higher frequency of complete dentures in females than in males and in the older age groups.