The aim of this study was to assess dentoskeletal and facial profile changes due to activator treatment in young adult patients with skeletal Class II malocclusion caused by mandibular retrognathism. The material of this study consisted of pretreatment (T1) and posttreatment (T2) lateral cephalometric head films of 21 (17 females and 4 males) patients treated with activator. The mean pretreatment age was 16.9 +/- 3.3 years and average treatment time was 12 +/- 2.2 months. Preand post-treatment cephalograms were evaluated and paired t-test was used to compare the significance of changes between both records. Activator treatment in the young adult patients resulted in correction of the Class II relationships, correction of the overjet and overbite, and improvement of the facial profile. The results of this study revealed that the activator appliance is effective in the treatment of Class II malocclusion in young adult patients. It is suggested that this treatment modality could be an alternative to orthodontic camouflage, orthognathic surgery and fixed functional appliance therapy in mild and borderline Class II cases.