To evaluate the use of Third Class Resolver (TCR), a new fixed and functional orthopaedic appliance for the treatment of skeletal Class III malocclusion in adolescents and young adults.Study design: Retrospective analysis. Twenty subjects, 10 females and 10 males, affected by Class III malocclusion were treated with a new fixed orthopaedic appliance: the Third Class Resolver (TCR). The mean age was 7 years at the beginning of treatment and 9 years at the end of treatment. The mean treatment time was 6 months. Digital cephalometric superimpositions on lateral radiographs taken at the start and end of treatment were assessed. The cephalometric values were statistically analysed.Cephalometric analysis of changes during treatment shows a statistically significant increase of ANB angle (mean 1°) (P = 0.045); increase of Witts Index (mean 3.5 mm) (P = 0.003); decrease of Maxillo-Mandibular angle (MM) (mean -2.3°) (P = 0.047); increase of Upper incisor-Maxilla Plane angle (angle mean 10.5°) (P = 0.02); increase of the distance between Upper Incisor and A-Pg line (mean 2.4 mm) (P = 0.021); increase of the mandibular branch length (mean 4.8 mm) (P = 0.004).TCR can be used fully for treatment of Class III malocclusions.