- Summary Objectives To evaluate the prevalence of nocturnal enuresis (NE) in children diagnosed with obstructive sleep apnea syndrome (OSAS) and the effect of tonsillectomy and adenoidectomy on enuresis. Design, setting, and participants All children 4–18 years of age who underwent polysomnography (PSG) between January 2003 and May 2004 were included (n = 161). The evaluation was based on a retrospective review of a standard sleep questionnaire and a full overnight PSG, followed by an additional structured telephone questionnaire performed 9 months after adenotonsillectomy (T&A) (range 5–14). Results We identified 144 (89%) children with an apnea hypopnea index >1. Of these 144 children, 42 [29.2% (95% CI, 21.8–36.6)] were reported to have enuresis, 27 of these 42 underwent T&A. Among the 27 enuretic children who had undergone adenotonsillectomy, 74.1% had 3 or more wet nights per week before the procedure compared to 37%, 1 month after [n = 27 (χ2 = 3.308, McNemar pv < 0.0001)]. Of the 27 children who underwent adenotonsillectomy, any decrease in enuresis severity was reported by 70.4% (95% CI 53.2–87.62), while in 56% of these 27 (95% CI 41.96–70.06) it occurred 1 month postoperatively. In 11/27 children (41%), enuresis totally disappeared within 1 month, while in 3/27 (11%) enuresis disappeared throughout the remaining time of follow-up. Conclusions Obstructive sleep apnea in children is frequently associated with nocturnal enuresis. Adenotonsillectomy has a favorable therapeutic effect on enuresis in children with obstructive sleep apnea presenting this symptom.