Objective To observe the efficacy of adenoidectomy and tonsillectomy in children with obstructive sleep apnea syndrome (OSAS). Methods Sixty children with OSAS were selected after a PSG(polysomnography) test. The children were randomily divided into group A (30 cases) or group B ( 30 cases). In group A, adenoids and/or tonsils were ablated, while vitamin C (0.1mg) was administered orally in group B. Apnea-hypopnea index (AHI) and lowest blood oxygen saturation (SaO2), before and after 3month treatment in the two groups, were tested. Clinical outcomes, in light of the language evaluation form（VRS）furnished by the parents, were also compared. Results No obvious difference of AHI and the lowest SaO2 before the treatment was found between the groups. However, after three months of treatment, AHI reduced to 2.6±1.8, and the lowest SaO2 increased to 92.9±2.5 in group A, in which all improved significantly compared with those before the treatment (P＜0.05). Also, AHI and lowest SaO2 in group B did not significantly change after the therapy (from 18.4±7.8 to 17.1 ±8.2, 79.2 ±11.4 to 81.4±9.1, respectively). According to the clinical outcomes, 86.7%, 93.3% and 86.7% of the children in group A improved in snore, and suffocation or mouth breathing which were all better than those in group B (6.7%,13.3%, and 13.3%,respectively;all P＜0.05). Conclusion Adenoidectomy and tonsillectomy are effective procedures to treat OSAS in children.