Despite the known influence of orthodontic treatment on facial appearance, there have been few comparative studies of the effect of different treatments, and none of these appear to have looked at the long-term consequences. This study compared the effect of traditional fixed appliances and orthotropic (growth guidance) treatment without fixed appliances on a series of 12 identical twins, 10 years after treatment. Facial changes were assessed by a panel of 12 lay judges. A comparison was also made of the dental changes and an error study undertaken. The results showed that most of the traditionally treated twins were judged to look less attractive after treatment, while most treated by orthotropics were judged to have improved. There was little difference in the dental results, but the traditionally treated cases seemed to relapse more frequently.