The aim was to examine dentoalveolar development in subjects with an 'ideal' (normal) occlusion. The material comprised 436 study casts of 189 male and 247 female subjects of Swedish origin between the ages of 5 and 31 years with no history of orthodontic treatment. Arch length, width, and depth, as well as palatal height were measured. The data were analysed with Student´s t-test. The results verified that continuous changes of the dental arches occur from the primary until the adult period, with individual variations. This change could be interpreted as a biologic migration of the dentition, resulting in anterior crowding especially in the mandible, even in subjects with congenitally missing third molars. The occlusion, thus, should be regarded as a dynamic rather than a stable interrelationship between the facial structures. This natural development has to be considered in orthodontic treatment planning as well as in assessment of stability following orthodontic treatment. A continuos increase of palatal height up to adulthood seems to be an effect of a slow continuous eruption of the teeth. This finding is of significance in explaining the infraposition of implant-supported crowns.