OBJECTIVE To investigate the therapeutic effect of obstructive sleep apnea hypopnea syndrome (OSAHS) by modified uvulopalatopharyngoplasty (UPPP). METHOD Forty-nine cases of OSAHS were treated by modified UPPP, and followed-up on 6 months, 1 year and 2 years after operation and carried out polysomnography (PSG) every time. RESULT Therapeutic effect was evaluated by standard of Hangzhou (2002) . In 6 months, symptoms of snore, breath holding, headache and lethargy disappeared or reduced obviously, the total effective rate was 100%. In 12 and 24 months, the effective rate was 95.92% and 91.84% respectively. CONCLUSION This operation can enlarge venting area of palatopharyngeal cavity effectively and keep density of soft palate as well as the normal function of pharyngeal mucous membrane, and can also elevate operative effect and decrease postoperative complications.