The aim of the study was to assess the role of serum osteoprotegerin (OPG) as a biomarker in patients with aortic valve stenosis (AS) in relation to heart failure and symptomatic status. This was a case control study, which included 51 patients with AS and 39 control subjects. At the time of study enrolment, detailed medical history was obtained and all subjects underwent physical examination, chest x-ray and echocardiography. OPG levels were measured in all subjects, and serum N-terminal of the pro b-type natriuretic peptide (NT pro BNP) levels were determined in patients with AS. Serum OPG levels were elevated in patients with AS compared to control subjects (p=0.001). Pa-tients with heart failure due to AS had elevated serum OPG levels in comparison to patients without heart failure (p=0.001). A significant correlation between OPG and symptomatic status was observed in all patients with AS (p<0.001), however, it was not the case in patients without heart failure (p=0.425). There was a positive correlation between OPG and NT pro BNP concentrations with objective signs of heart failure on chest x-ray (p<0.001). Negative correlation of OPG concentrations with aortic valve area was present (p<0.040), as well as with left ventricular ejection fraction (p<0.001). Serum OPG could be a valuable biomarker in the evaluation of severity of calcified AS and serve as an additional indicator besides clinical presentation and echocardiography in the assessment of surgical treatment or aortic valve replacement.