To　investigate　the　relativity　of　MGMT(O-6-methylguanine-DNA　methyltransferase)　gene　methylation　from　patients　with　protein　expression　and　osteosarcoma　necrosis　rate　after　chemotherapy.　Fifty-one　oteosarcoma　tissues　were　collected,　Methylation　of　MGMT　gene　promoter　was　detected　by　methylation-specific　PCR　method,　and　protein　expression　of　MGMT　was　examined　by　immunohistochemistry　procedure,　the　relationship　between　methylated　MGMT　gene　expression　and　patients　response　to　chemotherapy　was　analyzed.　The　positive　ratio　of　methylation　MGMT　gene　promoter　in　51　patients　was　23.5%　(12　in　51).　Negative　percentage　of　protein　expression　of　MGMT　was　27.5%　(14　in　51).　It　seemed　that　methylation　of　MGMT　gene　in　osteosarcoma　tissues　had　no　evident　relationship　with　the　patient＇s　age,　sexuality,　and　the　size　and　type　of　neoplasms,　etc.　The　necrosis　rates　of　methylated　MGMT　of　osteosarcoma　(tumor　grade　from　I　to　IV)　were　0　(0/51),　3.9%　(2/51),　5.9%　(3/51),　13.7%　(7/51),　respectively.　In　contrast,　the　necrosis　rates　of　unmethylated　MGMT　of　osteosarcoma　(tumor　grade　from　I　to　IV)　were　45.1%　(23/51),　25.5%　(13/51),　3.9%　(2/51),　2.0%　(1/51),　respectively.　It　suggest　that　methylated　and　unmethylated　MGMT　gene　of　osteosarcoma　have　significant　difference　in　protein　expression.　The　unmethylated　MGMT　gene　has　higher　positive　protein　expression　(u　=　-4.92,　P　＜　0.001).　Methylation　of　MGMT　gene　has　higher　tumor　necrosis　rate　in　osteosarcoma　patients.　Methylation　in　MGMT　promoter　may　be　important　for　judging　the　effect　of　chemotherapy　in　Osteosarcoma　patients.