Objective:To investigate the expressions of Mfn2(mitofusin 2) in non-small-cell lung cancer (NSCLC) tissues and non-cancerous lung tissues,and analyze its relationship with clinicopathological characteristics of lung carcinomas.Methods:The expressions of Mfn2 mRNA and protein in 92 cases of NSCLC tissues and 27 cases of non-cancerous lung tissues were detected by in situ hybridization and immunohistochemical methods. Results:The positive rates of Mfn2 mRNA and protein in pulmonary squamous cell carcinoma were higher than those in adenocarcinoma (83.33% and 89.58% vs 56.82% and 65.91%), respectively. The positive rates of Mfn2 mRNA and protein in NSCLC were higher than those in the non-cancerous lung tissues (25.93% and 29.63%) . The difference was statistically significant among the three groups (P<0.001 and P<0.01). The expressions of Mfn2 mRNA and protein in well-differentiated (93.75% and 100%) and moderately-differentiated NSCLC (91.67% and 91.67%) were higher than those in poor-diffe-rentiated NSCLC (21.43% and 42.86%). The difference was significant (P<0.001). The expressions of Mfn2 mRNA and protein had no correlation with the gender, age, tumor size, TNM stage and lymph node metastasis (P>0.05). The expression of Mfn2 mRNA was consistent with that of Mfn2 protein in NSCLC.Conclusion:Mfn2 was involved in the initiation and progression of lung cancer, and the expression of Mfn2 was related to the histological types of lung cancer and its differentiation degree.