The purpose of this study was to determine the effectiveness of adenotonsillectomy (T&A) for treating obstructive sleep apnea (OSA) in obese children. PubMed and Ovid databases. A meta-analysis of studies that reported sleep parameters in obese children with OSA before and after T&A. Data were analyzed using the random effects model. Statistical significance was P < or = 0.05. Data from four studies that included 110 children were analyzed. The mean sample size was 27.5 (range, 18-33). The mean body mass index z score was 2.81. The mean pre- and postoperative apnea-hypopnea index (AHI) was 29.4 (range, 22.2-34.3) and 10.3 (range, 6.0-12.2), respectively. The weighted mean difference between pre- and postoperative AHI was a significant reduction of 18.3 events per hour (95% confidence interval [CI], 11.2-25.5). The mean pre- and postoperative oxygen saturation nadir was 78.4 percent (range, 73.9%-81.1%) and 85.7 percent (range, 83.6%-89.9%), respectively. The weighted mean difference was a significant increase of the oxygen saturation nadir of 6.3 percent (95% CI, 3.9-8.7). Forty-nine percent of children had a postoperative AHI <5, 25 percent of children had a postoperative AHI <2, and 12 percent of children had a postoperative AHI <1. T&A improves but does not resolve OSA in the majority of obese children. The efficacy and role of additional therapeutic options require more study. The high incidence of obesity in children makes this a public health priority.