In studying a group of fifty adult females with Class II division 1 malocclusion, it was evident that the skeletal problems of this malocclusion involved small, retruded mandibles accompanied by backward rotation. This skeletal pattern was considered to be influenced by the vertical dimension of the upper dentition in the buccal segment for mandibular function. The anterior and the posterior occlusal planes were examined to gain a detailed assessment of the relationship between the dental and the skeletal patterns. The findings indicated that the steep cant of the posterior occlusal plane was strongly correlated with the following: 1. Small, retruded mandible with backward rotation as the skeletal pattern. 2. Short vertical height of the upper second molars and distal inclination of the upper molars as the dental pattern. The increased vertical height of the lower second premolars was found to be related to backward rotation of mandible. In treating skeletal Class II malocclusions, this study indicated that control of the vertical dimension of the posterior teeth is extremely important.