Depressive symptoms following adenotonsillectomy (AT) relative to controls were examined in children with obstructive sleep apnea syndrome (OSAS). 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. 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children reported more severe depressive symptoms (p = 0.026) and parents of overweight/obese children reported more withdrawn/depressed symptoms (p = 0.004).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with self-report depressed (r = -0.17, p = 0.028), parent-reported anxious/depressed (r = -0.15, p = 0.049), and withdrawn/depressed (r = -0.24, p = 0.002) symptoms. Increased risk for depressed and withdrawn/depressed symptoms was detected among children with OSAS, and different demographic variables contributed to risk in self-reported and parent-reported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. Childhood Adenotonsillectomy Study for Children with OSAS (CHAT), https://clinicaltrials.gov/show/NCT00560859, NCT00560859.