Matrix metalloproteinases 2, 7, 9 and tissue inhibitor of matrix metalloproteinase-1 in the sera of patients with bone tumors. Comparative enzyme immunoassay of matrix metalloproteinases (MMP-2, -7, -9) and their tissue inhibitor-1 (TIMP-1) in the sera of 26 healthy individuals and 54 patients with primary osteal tumors before therapy revealed elevated TIMP-1 levels in the patients with classical central and periosteal osteosarcomas in comparison with the control. In patients, the level of MMP-9 significantly decreased compared to that in healthy individuals, while the levels of MMP-2 and MMP-7 remained unchanged. No differences in serum levels of MMP and TIMP-1 associated with gender, age, primary osteal tumor location and size were detected. Overall 3-year survival of patients with classical central osteosarcoma with serum level of MMP-9 below its median was higher than that of patients with MMP-9 level equal to above the median (90.9 ± 8.7 and 50.8 ± 23%, respectively).