This randomized controlled trial evaluated the effectiveness of early adenotonsillectomy versus watchful waiting in children with obstructive sleep apnea syndrome (OSAS). The study included 464 children aged 5 to 9 years, with OSAS but no prolonged oxyhemoglobin desaturation. The primary outcome was the attention and executive-function score on the Developmental Neuropsychological Assessment, which showed no significant difference between the two groups. However, the early adenotonsillectomy group showed significantly greater improvements in behavioral, quality-of-life, and polysomnographic outcomes. The normalization of polysomnographic findings was more common in the early adenotonsillectomy group (79%) compared to the watchful-waiting group (46%). The study concluded that while early adenotonsillectomy did not significantly improve attention or executive function, it effectively reduced symptoms and improved secondary outcomes, supporting its use in treating OSAS.This randomized controlled trial evaluated the effectiveness of early adenotonsillectomy versus watchful waiting in children with obstructive sleep apnea syndrome (OSAS). The study included 464 children aged 5 to 9 years, with OSAS but no prolonged oxyhemoglobin desaturation. The primary outcome was the attention and executive-function score on the Developmental Neuropsychological Assessment, which showed no significant difference between the two groups. However, the early adenotonsillectomy group showed significantly greater improvements in behavioral, quality-of-life, and polysomnographic outcomes. The normalization of polysomnographic findings was more common in the early adenotonsillectomy group (79%) compared to the watchful-waiting group (46%). The study concluded that while early adenotonsillectomy did not significantly improve attention or executive function, it effectively reduced symptoms and improved secondary outcomes, supporting its use in treating OSAS.