OSAHS or snoring is an important condition within our community with the potential of being a significant health burden. Although the precise pathogenesis of upper airway obstruction during sleep remains uncertain in OSAHS and snoring patients, craniofacial risk factors are said to be associated with OSAHS and snoring. Since a high number of OSAHS and snoring patients consist of skeletal Class II malocclusion patients characterized by deficient mandible, then we can make the hypotheses that early orthodontic treatment of skeletal Class II malocclusion patients to improve such discrepancies during the growth period may be effective to prevent the potential for OSAHS and snoring.