BACKGROUND Adenotonsillectomy is the treatment of choice for most children with obstructive sleep apnea syndrome, but can lead to complications. Current guidelines recommend that high-risk children be hospitalized after adenotonsillectomy, but it is unclear which otherwise-healthy children will develop post-operative complications. We hypothesized that polysomnographic parameters would predict post-operative complications in children who participated in the Childhood AdenoTonsillectomy (CHAT) study. METHODS Children in the CHAT study aged 5-9 years with apnea hypopnea index 2-30/h or obstructive apnea index 1-20/h without comorbidities other than obesity/asthma underwent adenotonsillectomy. Associations between demographic variables and surgical complications were examined with Chi square and Fisher's exact tests. Polysomnographic parameters between subjects with/without complications were compared using Mann-Whitney tests. RESULTS Of the 221 children (median apnea hypopnea index 4.7/h, range 1.2-27.7/h; 31% obese), 16 (7%) children experienced complications. 3 (1.4%) children had respiratory complications including pulmonary edema, hypoxemia and bronchospasm. Thirteen (5.9%) had non-respiratory complications, including dehydration (4.5%), hemorrhage (2.3%) and fever (0.5%). There were no statistically significant associations between demographic parameters (gender, race, and obesity) or polysomnographic parameters (apnea hypopnea index, % total sleep time with SpO2<92%, SpO2 nadir, % sleep time with end-tidal CO2>50Torr) and complications. CONCLUSIONS This study showed a low risk of post-adenotonsillectomy complications in school-aged healthy children with obstructive apnea although many children met published criteria for admission due to obesity, or polysomnographic severity. In this specific population, none of the polysomnographic or demographic parameters predicted post-operative complications. Further research could identify the patients at greatest risk of post-operative complications.