A sample of 47 untreated children (M 32:F 15) with Class II Division 1 (II/1) deep-overbite malocclusion was collected from a group of patients who declined orthodontic therapy. Longitudinal records consisted of plaster dental casts and lateral cephalograms at original diagnosis and plaster dental casts at a follow-up observation in adulthood, an average of 11.5 years later. To study retrospectively natural changes in dental occlusion during this interval, plaster-cast millimetric measurements were recorded of sagittal dental relationships (first molar and canine), overjet, overbite, and crowding/spacing at the two registrations. Results showed statistically significant improvements in untreated II/1 deepbite malocclusion from adolescence to adulthood for all measured occlusal variables except development of mild crowding. Therefore, assumptions that untreated II/1 distoclusion will worsen with age appear to be unfounded. The evidence indicates that the absence of orthodontic correction for adolescent patients with Class II Division 1 deepbite malocclusion will not usually lead to measurable occlusal deterioration in young adulthood.