The purpose of this study was to compare the treatment outcome and long-term stability of 2 groups of young adult patients diagnosed with active condylar hyperplasia and treated with 2 different surgical methods. Thirty-seven patients (19 females and 18 males) met the criteria for inclusion in the study. Group 1 (n = 12; average age at surgery, 17.5 years) was treated with orthognathic surgery only, while group 2 (n = 25; average age at surgery, 16.7 years) had high condylectomy, articular disc repositioning, and orthognathic surgery. All patients underwent standardized clinical and radiographic examination at initial consultation, immediately before surgery, immediately after surgery, and at longest follow-up. Objective evaluation of temporomandibular joint (TMJ) function included maximum incisal opening and lateral excursions. Subjective evaluations were performed in group 2 for TMJ pain, jaw function, and diet. Lateral cephalometric radiographs were evaluated for presurgical and postsurgical mandibular growth. There were no statistically significant differences (P >.05) between the 2 groups for maximal incisal opening, lateral excursions, or subjective jaw function before surgery. Presurgical growth differed significantly (P <.05), with group 2 showing more active growth. At the long-term follow-up, no differences were found in lateral excursions or subjective jaw function. There was a statistically significant difference in maximum incisal opening (P <.01), with a greater increase in group 2, as well as a statistically significant difference (P <.05) in cephalometric stability, with group 2 being much more stable at long-term follow-up. All patients in group 1 grew back into skeletal and occlusal Class III relationships and required secondary intervention. Only 1 patient in group 2 required secondary surgery, involving maxillary surgery to correct postsurgical transverse maxillary relapse; the mandible was stable at long-term follow-up. The results of this study showed that patients with active condylar hyperplasia treated with high condylectomy, articular disc repositioning, and orthognathic surgery have stable, predictable outcomes compared with those treated with orthognathic surgery alone.