Seven-hundred-and-ninety-one 15-year-olds were subjected to an anamnestic and clinical examination of craniomandibular disorders. These individuals had been examined at the age of 12 years and this is one section of an extensive longitudinal investigation into the effects of malocclusion, and the effectiveness of orthodontic treatment. The children were originally selected on the basis of presence of malocclusion. Signs of CMD were found in about half of the subjects. The proportion of individuals without any signs of CMD had decreased during the 4-year period. However, the number of subjects with severe signs remained very small. Changes in severity of CMD according to Helkimo's index of clinical dysfunction were mainly attributed to an increased prevalence of impaired TMJ function. An increase in prevalence of reported symptoms was found involving headache and joint sounds. The other recorded symptoms did not show any significant increase in prevalence. Mandibular mobility showed only minor changes from 12 to 15 years of age.