Abstract: AIM:To analyze the relation between osteoprotegerin (OPG) and B-type natriuretic peptide (BNP) levels in patients with acute coronary syndrome (ACS). METHODS: One hundred and sixty consecutive patients were classified into two groups: acute coronary syndrome (ACS) and control group. OPG and BNP were measured upon hospital admission and compared in relation to the number of narrowed coronary vessels (1-, 2-, 3-vessel disease) and to the degree of stenoses according to Gensini score. RESULTS: Serum OPG and BNP levels were significantly higher in patients than in controls (P<0.001) and the levels increased significantly with the degree of severity. A positive relation was found between OPG levels and Gensini score (P<0.01), whereas sRANKL levels and Gensini score and hs-CRP levels were negatively correlated (r=0.61, P<0.01). Only a mild correlation was found between BNP and Gensini score (r=0.34, P<0.01). Multiple regression analysis showed that OPG and BNP levels were independently and positively associated with the presence of coronary diseases (P<0.01 respectively). CONCLUSION: Serum OPG and BNP levels and the severity of ACS are related, suggesting that they may be involved in the process of coronary artery disease.