Aim: To analyze the effectiveness of the Twin Force Bite Corrector in 2 patients requiring anterior advancement of the mandible. Methods: To correct the imbalanced maxillomandibular relationship, a Twin Force Bite Corrector was inserted in 2 female adolescents (case 1: 12 years 3 months of age; case 2: 12 years 7 months of age) presenting with a skeletal Class II malocclusion. The pretreatment, posttreatment, and follow-up dental and skeletal parameters were evaluated on lateral cephalometric radiographs. Twenty-two reference points were marked and 23 variables measured for each set of lateral cephalograms. Results: The Twin Force Bite Corrector therapy lasted for 3 months in both patients. The total orthodontic treatment duration was 1 year 4 months for case 1 and 1 year 6 months for case 2. In both patients, the overjet reduced, the mandibles advanced, and a Class I molar relationship was achieved. Effective mandibular length (Co-Gn) increased significantly, while the mandibular incisors almost kept their initial positions without a significant change in inclination (L1/ML). The clinical profiles of both girls remarkably improved. Conclusions: The Twin Force Bite Corrector was effective in the correction of skeletal Class II malocclusion with retrognathic mandible, with negligible anchorage loss in the mandibular arch. World J Orthod 2008;9:267.