This study compared the effectiveness of flexible laryngeal mask (F-LMA) insertion and endotracheal intubation in pediatric patients undergoing adenotonsillectomy surgery. A total of 60 patients aged 2-12 years were included in the study. Patients were divided into the F-LMA group (n=30) and endotracheal tube (ETT) group (n=30). The groups were compared according to intubation time, heart rate, SpO 2 , EtCO 2 , airway pressure, surgical field of view, and recovery time. Both the insertion time and recovery time were shorter in the F-LMA group than in the ETT group (16.93±4.84 s vs. 23.93±8.74 s; and 10±2 min vs. 14.5±3 min; p<0.001 both). The airway pressure measurements at 5-min intervals were significantly lower in the F-LMA group than in the ETT group (p<0.001). F-LMA may be a useful alternative to ETT for adenotonsillectomy surgery because it is safe, provides shorter induction and recovery times, reduces intraoperative airway pressure, and provides an adequate operative field of view.