Objective To investigate the effect of dexmedetomidine (Dex) on the apoptosis and respiratory burst of human polymorphonuclear neutrophils (PMN) in vitro. Methods The peripheral venous blood was collected from healthy volunteers. Isolation of PMN was performed by using the discontinuous plasma-Percoll gradient technique. PMN was randomLy divided into four groups: control group and three different concentrations of Dex (1 ng/mL,10 ng/mL,100 ng/mL) groups. PMN was cultured in enriched RPMI-1640 media at 2 × 106/mL for 24 h. The caspase-3 activity, apoptosis rate and respiratory burst of PMN were detected at 2 and 24 h. Results Compared with the control group, the PMN which was treated with three different concentrations of Dex showed no significant difference in caspase-3 activity, apoptosis rate and respiratory burst of PMN after 2 h of incubation. Compared with the control group, 1 ng/mL concentration of Dex did not affect the caspase-3 activity, apoptosis and respiratory burst of PMN cultured for 24 h. However, 10 ng/mL and 100 ng/mL concentrations of Dex promoted the caspase-3 activity, increased apoptosis rate and reduced the respiratory burst of PMN after 24 h of incubation. Compared with 10 ng/mL Dex group, 100 ng/mL concentrations of Dex promoted the caspase-3 activity, increased apoptosis rate and reduced the respiratory burst of PMN after 24 h of incutation. Conclusion Clinically relevant concentration of Dex does not affect apoptosis and respiratory burst of PMN, while high concentration of dexmedetomidine can induce apoptosis of PMN.