Abstract: Objective: To analyze the relationship between serum osteoprotegerin(OPG) and glycated hemoglobin(HbA1c) levels in patients with acute coronary syndrome(ACS).Methods: Eighty-eight patients were classified into control group,stable angina pectoris(SAP) group and ACS group.Serum OPG and HbA1c levels were measured upon hospital admission and divided into 1-,2-,3-vessel disease groups according to the numbers of narrowed coronary vessels under coronary angiography.The relationships of serum OPG and HbA1c levels and coronary stenosis degree according to Gensini score were analyzed.Results: Serum OPG and HbA1c levels in ACS group were significantly higher than in control group(P 0.01),and OPG and HbA1c levels were increased significantly with the severity degree of ACS(P 0.05-P 0.01).A positive relationship was found between OPG level and Gensini score(P 0.01),and a positive correlation was also found between HbA1c level and Gensini score(P 0.01).OPG level was positively correlated with HbA1c level(P 0.01).Conclusions: Serum OPG and HbA1c levels were related with the severity of ACS.