Abstract: Objective To explore the effect of small dose of fentanyl combined with midazo-lam on prevention of radial artery spasm.Methods 1086 patients with elective transradial percuta-neous coronary intervention were randomly divided into medicine group and control group.The medicine group was treated with conventional intravenous injection of fentanyl and midazolam.Inci-dence rate of radial spasm,vascular complications and mortality rate or re-hospitalization rate with-in 30 days were recorded and compared between two groups.Results Incidence rate of radial spasm in medicine group was 2.5%,which was significantly lower than 8.8% in the control group (P <0.001).There were no significant differences in aspects of VAS score,mortality rate and re-hos-pitalization rate between two groups.Multivariate analysis showed that there were obvious correla-tion between incidence of radial spasm and gender,height,obesity,smoking,numbers of tubes, surgical way and difficulty of operation.Conclusion Small dose of fentanyl combined with midazo-lam during transradial interventional procedures can significantly reduce the incidence of radial spasm and vascular complications,and it won’t cause increasing of mortality rate and re-hospitalization rate.