Rationale: Adenotonsillectomy, the first line of treatment of sleepdisordered breathing (SDB), is the most commonly performed pediatric surgery. Predictors of the recurrence of SDB after adenotonsillectomy and its impact on cardiovascular risk factors have not been identified. Objectives: Demonstrate that gain velocity in body mass index (BMI) defined as unit increase in BMI/year confers an independent risk for the recurrence of SDB 1 year after adenotonsillectomy. Methods: Children with SDB and hypertrophy of the tonsils and a comparison group of healthy children were followed prospectively for 1 year. Measurements and Main Results: Serial polysomnographies, BMI, and blood pressure were obtained before adenotonsillectomy and 6 weeks, 6 months, and 1 year postoperatively. Gain velocity in BMI, BMI and being African American (odds ratios, 4-6/unit change/yr; 1.4/unit and 15, respectively) provided equal amounts of predictive power to the risk of recurrence of SDB. In the group that experienced recurrence, systolic blood pressure at 1 year was higher than at baseline and higher than in children who did not experience recurrence. Conclusions: Three clinical parameters confer independent increased risk for high recurrence of SDB after adenotonsillectomy: gain velocity in BMI, obesity, and being African American. A long-term follow-up of children with SDB and monitoring of gain velocity in BMI are essential to identifying children at risk for recurrence of SDB and in turn at risk for hypertension. Keywords: growth velocity; adenotonsillectomy; sleep-disordered breathingOne of the most frequently encountered conditions associated with obesity is sleep-disordered breathing (SDB). In adults, the risk of SDB increases by 1.14 for every unit increase in body mass index (BMI) (1). In the pediatric population, the risk for developing SDB is fourfold greater in obese children than in children who are not obese (2). Although the prevalence of SDB in all children is believed to range from 2 to 3% (3-5), the prevalence in adolescents who are morbidly obese exceeds 50% (6, 7). Obesity is therefore strongly associated with abnormal upper airway control during sleep across all age groups.Adenotonsillectomy, the first line of treatment in the management of childhood SDB, is the most commonly performed surgical procedure in children. The annual rate of adenotonsillectomy in children aged 0 to 14 years ranges from 19 per 10,000 in Canada to 115 per 10,000 in the Netherlands (8). At least half of these procedures are performed to relieve symptoms of SDB. In the first few weeks after adenotonsillectomy, obese children with SDB have a less favorable response to surgery than lean children. However, neither the long-term outcome nor the factors that contribute to recurrence of the disorder after adenotonsillectomy are clearly understood. Moreover, the impact of recurrence of SDB on important cardiovascular risk factors, such as blood pressure (BP), has never been examined.Research investigating the relationship between adiposity and SDB h...