The aim of this study was to evaluate the skeletal and dentoalveolar changes achieved by a modified protractor in growing skeletal and dental Class III patients and to compare these changes with normal growth in a Class I untreated control group. The study group consisted of 25 patients (11 girls, 14 boys; mean age 11.74 +/- 1.81 years). The control group was composed of 20 patients (15 girls, five boys; mean age 11.89 +/- 1.08 years). The Class III patients were treated with a bonded acrylic cap splint type expander and a modified maxillary protractor until a positive overjet was achieved. The mean observation period was 0.65 years. Changes in study and control groups and differences between the groups were analyzed statistically. The results showed that protraction appliance produced a significant positive improvement in maxillo-mandibular relations. The forward movement of the maxilla was significant in treated Class III patients, but a slight difference was present between the two groups regarding maxillary rotation. The effective length of the maxilla was significantly increased in the Class III patients. The mandible was positioned backward, and posterior rotation of the mandible was significant in the treatment group. There was a significant increase in lower anterior facial height of treated Class III patients. The dentoalveolar measurements showed that the maxillary incisors proclined and the mandibular incisors significantly retroclined in the Class III group. A modified maxillary protractor treatment is effective for correcting skeletal Class III malocclusion.