BACKGROUND It has been proven that CC chemokine receptor 7 (CCR7) is closely related with the lymph node metastasis of non-small cell lung cancer (NSCLC), but the mechanism of NSCLC metastasis is not very clear. The aim of this study is to investigate the expressions of CCR7 and MMP-9 in NSCLC and the relationship of their expressions, and to explore the mechanism of CCR7 promoting NSCLC metastasis. METHODS The expressions of CCR7 and MMP-9 protein were detected in 90 specimens of human primary NSCLC by immunohistochemical SP method. Human large lung cell line BE1 cells were pre-incubated with CCL19 for 24 h; the changes of MMP-9 were detected by RT-PCR and Western blot. RESULTS Immunohistochemistry showed that CCR7 was distributed in cytoplasm and/or membrane of tumor cells and MMP-9 was distributed in cytoplasm of cancer cells. The expressions of CCR7 and MMP-9 protein were found to be 70% (63/90) and 65.5% (59/90) in NSCLC, respectively. The expressions of CCR7 and MMP-9 protein were closely related to the clinical stages (P=0.003, P=0.001) and lymph node metastasis (P=0.004, P=0.003) of NSCLC, but there was no correlation with age, gender, histology (P > 0.05). Furthermore, a significant correlation was found between CCR7 and MMP-9 (r=0.342, P=0.001). In addition, the expressions of MMP-9 mRNA and protein levels were increased in CCL19 pre-incubated group (P < 0.05). CONCLUSIONS The expressions of CCR7 and MMP-9 are significantly associated with NSCLC invasion and metastasis. The upregulation of MMP-9 is regulated by CCR7 in NSCLC.