Objective:To determine the plasma level of copeptin in patients with coronary heart disease,and to discuss its diagnostic value for severity of coronary atherosclerosis.Methods: Coronary angiography (CAG) was performed in 180 hospitalized patients with suspected coronary heart disease (CHD).The 180 patients were divided into two groups: CHD group (n=101) and non-CHD group (control,n=79) based on the results of CAG.The CHD group was further divided into subgroups according to the number of diseased coronary branches and Gensini’s score: one-vessel subgroup (38),two-vessel subgroup (34) and three-vessel subgroup (29),0＜Gensini’s score＜20 subgroup (40),20≤Gensini’s score＜40 subgroup (29) and Gensini’s score≥40 subgroup (32).Plasma copeptin,lipids,fasting plasma glucose,blood pressure,and body mass index were measured before CAG in all patients; age,sex, and prior medical histories including hypertension,diabetes mellitus, and smoking status were also obtained.Plasma copeptin was determined by radioimmunoassay (RIA) and were compared between different groups.Results: Plasma copeptin level(ng/ml) in CHD patients was significantly higher than that in the controls (0.953 6±0.098 6 vs 0.924 4±0.064 9,P<0.05).Plasma copeptin levels in two-vessel subgroup and three-vessel subgroup were significantly higher than those in the control and one-vessel subgroup (P＜0.05),with no significant difference found between the former two groups.Plasma copeptin levels in 20≤Gensini’s score＜40 subgroup and Gensini’s score≥40 subgroup were significantly higher than those in the control group and 0＜Gensini’s score＜20 subgroup (P＜0.05),with no significant difference found between 20≤Gensini’s score＜40 subgroup and Gensini’s score≥40 subgroup.Conclusion: Plasma copeptin in CHD patients is at a higher level,and to some extent it can reflect the severity of coronary atherosclerosis,but has little value in identification of severe coronary heart diseases.