Aim of the study was evaluation of level of MGP (matrix GLA protein) in serum end-stage osteoarthritis patients. 12 end-stage osteoarthritis patients and 14 healthy persons were included in the study. Serum level matrix GLA protein (MGP) was measured by ELISA technique. MGP concentration in the serum osteoarthritis patients was lower than in the controls. Patients and healthy persons were of similar age. Serum MGP level was independent of age of osteoarthritis patients and healthy persons. Concentration of MGP in serum of osteoarthritis patients who had joint pain for a long time was lower than in the serum of osteoarthritis patients with shorter time of arthralgia. A weak negative correlation between time from beginning of joint ailment to total arthroplasty and matrix GLA protein level in serum was observed. The ROC curve suggests that serum MGP concentration is a very useful test for diagnosis of end-stage osteoarthritis. Low concentration of MGP in serum may be the cause of articular cartilage calcification during osteoarthritis. Serum MGP level seems to be a useful biochemical marker for laboratory diagnosis of osteoarthritis.