Abstract： Objective To obseTve the correlation among Nitric Oxide Synthase(NOS)activity,Serum Uric Acid(SUA)level and smoking index in male essential hypertension(EH)patients and to provide theoretical evidence for the pathogenesis.prevention and treatment of EH.Methods A total of 168 men were enrolled.Study group included 100 cases who were EH patients and control group had 68 healthy men.According to smoking condition,the study group was subdivided into two groups:smoking group and non-smoking group.The activity of NOS and inducible Nitric Oxide Synthase(iNOS)were determined with chemistry colorimetry.The SUA level was detected with enzymology.Then the smoking index was calculated.Results The general activities of NOS、iNOS of EH patients were signitlcandy lower and SUA of EH patients were obviously higher than that of the control group.The SUA concentrations between the smoking and non-smoking subgroups had a statistical difference(P＜0.05).The linear correlation analysis showed there was a positive relation between smoking history and serum uric acid level.Simultaneously,there was a positive relation between SUA level and iNOS with a correlation coefficient 0.568 (P＜0.01).Conclusion The levels of serum NOS、iNOS activity、UA and smoking history were closely related to EH while The level of SUA was related to smoking history,and SUA is related to iNOS.