Objective To assess ventilation administration during fiberoptic bronchoscopy (FB) in neonates. Methods Twenty-three neonates divided into two group (A group 12 neonates, B group 11 neonates) received FB. All were given pressure support ventilation (PSV)by a Y-like facility which connected to fiberoptic bronchoscope suction hole. In A group,after the tip of fiberoptic bronchoscope arrived at the carina, PSV was administrated. In B group, PSV was administrated in the entire process during FB, SpO2 and electrocardio were monitoring. Artery blood samples for blood gas analysis were obtained at four stages of just before FB,with the tip of the bronchoscope at the supralarynx,just before withdrawing bronchoscope out off trachea and within 20-30 minutes after FB. The arterial blood oxygen tension (PaO2), arterial blood carbon dioxide tension (PaCO2) and SpO2 just before FB served as baseline. The same indexes of other three stages were compared with the baseline. Results All 23 neonates were studied completely. When the tip of fiberoptic bronchoscope advanced from nostril to the supralarynx, SpO2, PaO2 and PaCO2 in two groups were similar to the baseline. In A group, when the tip below the glottis, cyanosis occurred, and SpO2 decreased significantly ( P＜0. 01 ) in 11 cases (92%) by 25% ; When tip at the carina, after PSV, cyanosis disappeared, and SpO2 returned to the baseline level, PaO2 keep on the baseline just before withdrawing the bronchoscope out of the trachea. SpO2 ,PaO2 in all B group neonates keep on the baseline during FB. After the tip below the glottis,PaCO2 in all neonates of the two groups increased significantly ( P＜0. 01 ), but returned to baseline within 20-30 minutes after FB. Conclusion FB can cause significant hypoxemia and hypercapnia in neonates. PSV through fiberoptic bronchoscope can be considered a safe and beneficial ventilation technique for maintaining oxygenation during FB.