Abstract: Objective To investigate the correlations between the expressions of matrix metalloprpteinsae 26(MMP-26),tissue inhibitor of metalloproteinase-4 (TIMP-4) and matrix metalloprpteinsae-9 (MMP-9) in patients with Extranodal natural-type NK/T-cell lymphoma (ENKTCL) and invasion of ENKTCL. Methods Expressions of MMP-26, TIMP-4 and MMP-9 were tested by SABC immunohistochemistry in 30 Specimens excised from ENKTCL patients, compairing with 20 cases of reactive lymphoid hyperplasia. The correlation between the expression levels and ENKTCL clinicopathology indexes were analyzed. Results The expression positive rates of MMP-26,TIMP-4 and MMP-9 in ENKTCL were 76.67%(23/30), 46.67%(14/30) and 83.33%(25/30) respectively, and signifi cant higher than those??10%(2/20), 5%(1/20) and 15%(3/20) in patients with reactive lymphoid hyperplasia(P<0.05). The positive expression rates of MMP-26 and MMP-9 were linked to clinical staging but age and gender (P > 0.05). The positive protein expressions in Stage Ⅲ and Ⅳwere higher than those in stageⅠand Ⅱ(P < 0.05), And there was no correlation between the expression of TIMP-4 and clinical staging, age or gender (P > 0.05). MMP-26 expression was related to MMP-9 (rs= 0.636, P <0.05), not to TIMP-4 in patients with ENKTCL (P > 0.05). Conclusion Highexpressions of MMP-26 and MMP-9 in patients with ENKTCL were related to the biological progression and invasiveness of ENKTCL and were malignant indicators to identify ENKTCL from reactive lymph node hyperplasia. MMP-26 and MMP-9 might play roles to assess ENKTCL prognosis.