A longitudinal investigation of changes of signs and symptoms of mandibular dysfunction over four to five years was performed, by means of questionnaires and clinical examination, in 240 children, ages 7, 11, and 15 years at the first examination. The objective of this part of the study was to analyze correlations between some occlusal and other factors, and mandibular dysfunction. Signs and symptoms of mandibular dysfunction increased slightly in both frequency and severity but were judged to be mild in most cases. Several types of occlusal interference were frequently recorded at both examinations. Dental wear increased during the follow-up period, while the results of evaluations of motor activity and psychological traits were relatively constant. There were only a few significant correlations, most of which were weak, between the recorded variables and mandibular dysfunction, and those found were not consistent in all age groups. TMJ sounds were positively correlated with lateral deviation of the mandible between retruded contact and intercuspal position in all age groups. An attempt to analyze the longitudinal relationship of occlusal interference with signs and symptoms of mandibular dysfunction did not reveal any strong correlations. The results are interpreted as supporting the heterogeneous and multifactorial nature of functional disturbances of the masticatory system.