OBJECTIVES: Determination of the serum levels of Receptor Activator of Nuclear Factor-Κb Ligand, bone-specific alkaline phosphatase, osteocalcin and osteoprotegerin in patients suffering from osteoarthritis of varying severity and healthy controls and correlation of these results with the patients' age and the radiographically assessed severity of the disease. DESIGN AND METHODS: Patients suffering from hip (n=58) or knee (n=117) osteoarthritis and matched controls (n=19) were enrolled in this study. Patients underwent physical examination and standard radiographic evaluation before blood sampling. RESULTS: The serum levels of osteoprotegerin were positively correlated with age in all groups, whereas those of osteocalcin in the 'knee' group only. Osteoarthritis' severity and location did not have a statistically significant impact on the mean serum level of any marker in both groups. CONCLUSIONS: Based on our results, none of the studied markers can serve as a surrogate for radiographic imaging in patients suffering from hip and knee osteoarthritis.