Rationale: Adenotonsillectomy, the first line of treatment of sleep disordered breathing is the most commonly performed pediatric surgery. Predictors of the recurrence of sleep disordered breathing after adenotonsillectomy and its impact on cardiovascular risk factors have not been identified. Objectives: Demonstrate that gain velocity in body mass index defined as unit increase in body mass index / year confers an independent risk for the recurrence of sleep disordered breathing 1 year after adenotonsillectomy. Methods: Children with sleep disordered breathing and hypertrophy of the tonsils and a comparison group of healthy children were followed prospectively for one year. Measurements and Main Results: Serial polysomnographies, body mass index and blood pressure were obtained before adenotonsillectomy and 6 weeks, 6 months and 1 year postoperatively. Gain velocity in body mass index, body mass index and being African American (odds ratios 4-6 /unit change/year, 1.4 /unit and 15 respectively) provided equal amounts of predictive power to the risk of recurrence of sleep disordered breathing. In the group with recurrence, systolic blood pressure at 1 year was higher than their baseline and higher than children without recurrence. Conclusion: Three clinical parameters confer independent increased risk for high recurrence of sleep disordered breathing after adenotonsillectomy: gain velocity in body mass index, obesity and being African American. A long-term follow-up of children with sleep disordered breathing and monitoring of gain velocity in body mass index are essential to identifying children at risk for recurrence of sleep disordered breathing and in turn at risk for hypertension.