This study evaluated the effect of positive end-expiratory pressure (PEEP) on optic nerve sheath diameter (ONSD), an indicator of intracranial pressure, in pediatric patients undergoing craniotomy in the supine position. The findings indicated that the application of PEEP did not result in a significant difference in ONSD. Although a significant decrease in systolic and diastolic blood pressure was observed with the use of PEEP, these values remained within normal ranges and did not indicate adverse hemodynamic effects. The results suggest that the use of a PEEP level of 4 cmH2O in pediatric patients with intracranial masses is safe and may be applied during the perioperative period.