Two brothers aged 15 1/6 and 12 2/3 years were diagnosed as Class I malocclusion with ectopic eruption of the upper left central incisor in the elder brother and etopic eruption in the upper right second premolar in the younger. All 4 second molars were extracted at the same time in both brothers. The treatment results were as follows. 1. In the elder brother, the third molars were fully erupted and their angulations were excellent at 3 years post-treatment. 2. In the younger brother, the lower right third molar was mesially erupted and upper third molars were still undergoing eruption at 3 years post-treatment. 3. Assessment of panex films of both brothers at aged 15 showed an earlier eruption of the third molars in the younger brother. 4. A longer post-treatment supervision of the third molars was required in the younger brother. 5. The facial probiles were enhanced and the ectopic eruptions were corrected in both brothers.