Objective To investigate the effect of isoflurane pretreatment on hypoxia/reoxygenation (H/R)-induced syndecan-1 shedding from human umbilical vein endothelial cells (HUVECs) . Methods HUVECs were cultured in EMB-2 medium and randomly divided into 3 groups ( n = 32 each) : control group (group C), H/R group and isoflurane pretreatment group (group I). H/R was produced by 4 h exposure of HUVECs to hypoxia followed by 2 h reoxygenation in H/R and I groups. HUVECs were exposed to the mixture of 5% CO2 and 95% O2 for 30 min and then cultured in normal culture atmosphere (21% O2) in group C. In group I, HUVECs were expased to 1.73% isoflurane and incubated for 30 min before H/R. The syndecan-1 expression, concentrations of shed syndecan-1 in the medium, and cell permeability and viability were measured at the end of reoxygenation. Results Compared with group C, the shed syndecan-1 concentration in the medium and cell permeability were significantly increased, while the syndecan-1 expression and cell viability decreased in H/R and Ⅰ groups ( P ＜ 0.01) . Compared with group H/R, the shed syndecan-1 concentration in the medium and cell permeability were significantly decreased, while the syndecan-1 expression and cell viability increased in group Ⅰ (P ＜ 0.01) . Conclusion Isoflurane pretreatment can protect HUVECs against H/R injury through inhibiting the syndecan-1 shedding.