Study Objectives: Depressive symptoms following adenotonsillectomy (AT) relative to controls were examined in children with obstructive sleep apnea syndrome (OSAS). Methods: The Childhood Adenotonsillectomy Trial (CHAT) multisite study examined the impact of AT in 453 children aged 5 to 9.9 years with polysomnographic evidence of OSAS without prolonged desaturation, randomized to early adenotonsillectomy (eAT) or watchful waiting with supportive care (WWSC). One hundred seventy-six children (eAT n = 83; WWSC n = 93) with complete evaluations for depressive symptomatology between baseline and after a 7-month intervention period were included in this secondary analysis. Results: Exact binomial test assessed proportion of depressive symptomatology relative to norms, while effects of AT and OSAS resolution were assessed through linear quantile mixed-models. Treatment group assignment did not significantly impact depression symptoms, although self-reported depression symptoms improved over time (p < 0.001). Resolution of OSAS symptoms demonstrated a small interaction effect in an unexpected direction, with more improvement in parent ratings of anxious/depressed symptoms for children without resolution (p = 0.030). Black children reported more severe depressive symptoms (p = 0.026) and parents of overweight/obese children reported more withdrawn/depressed symptoms (p = 0.004). Desaturation nadir during sleep was associated with self-report depressed (r = -0.17, p = 0.028), parent-reported anxious/depressed (r = -0.15, p = 0.049), and withdrawn/depressed (r = -0.24, p = 0.002) symptoms. Conclusions: Increased risk for depressed and withdrawn/depressed symptoms was detected among children with OSAS, and different demographic variables contributed to risk in self-reported and parent-reported depression symptoms. Arterial oxygen desaturation nadir during sleep was strongly associated with depressed symptoms. However, despite improvements in child-reported depressed symptoms over time, changes were unrelated to either treatment group or OSAS resolution status. Trials Registration: Childhood Adenotonsillectomy Study for Children with OSAS (CHAT), https://clinicaltrials.gov/show/NCT00560859, NCT00560859.