The aim of this work was to compare the skeletal and dental outcomes of 1- versus 2-phase treatment in Class II subjects with difficult-to-treat high-angle severe Class II malocclusions.The sample of 120 cases was collected from the private offices of 3 experienced clinicians. The following selection criteria were used: (1) ANB ≥6°, (2) SN-GoGn ≥37° or mandibular plane to Frankfort horizontal plane ≥30°; and (3) overjet ≥6 mm. Patients were classified into either the early or the late treatment group according to dental age (early Tx: ≥5 primary teeth; late Tx: otherwise). Thirty-four angular, linear, and proportional measurements were determined for each patient. Statistical significance was assessed with the use of a 2-tailed t test, analysis of covariance test, and chi-square test.The results showed that early 2-phase treatment for severe Class II high-angle patients offered no skeletal anteroposterior advantages over late 1-phase treatment. Severe high-angle Class II patients also showed similar dental anteroposterior outcomes with the use of both approaches. Vertically there was a higher frequency of increased mandibular plane angles and extrusion of upper incisors and lower molars in the late treatment group.Early 2-phase treatment for severe Class II high-angle patients offered no skeletal or dental advantage over late 1-phase treatment.