Objective: Neonates were monitored with a cerebral oximeter before, during, and after cannulation for ECMO to determine the direct effects of ligation of the right internal jugular vein and right carotid artery on cerebral oxygenation.Study Design: After obtaining informed consent, we used the FORE-SIGHT Cerebral Oximeter (CAS Medical Systems, Branford, CT, USA) to monitor neonates undergoing surgical preparation for veno-arterial (VA) or veno-venous (VV) extracorporeal membrane oxygenation (ECMO).Result: A total of 17 subjects were monitored pre-ECMO for atleast 48 h after cannulation. Of the 17 subjects, 12 experienced low cerebral tissue oxygen saturation (SctO 2 ) <60% during pre-ECMO surgery, with most exhibiting the lowest SctO 2 values between cannulation to the onset of ECMO. Two subjects received cardiopulmonary resuscitation (CPR) during surgery and experienced very low SctO 2 (5 and 36%). Pulse oximetry was found to be unreliable during CPR because of diminished pulsatile flow. SctO 2 increased above 60% after the onset of ECMO for all subjects and remained stable. Conclusion:Neonates are vulnerable to SctO 2 during the pre-ECMO surgical period.