Abstract： Objective To assess risk factors in NSCLC with N2 metastasis.Methods A total of 177 NSCLC patients (109 males,68 females; age:(60.1 ± 10.6) years) who underwent both 18F-FDG PET/CT scan and surgery were enrolled.They were divided into two groups.One was with N2 metastasis (N2+) and the other was without (non-N2+).The gender,age,location,size,primary tumor SUVmax,histopathologic type and differentiation grade between N2+ group and non-N2+ group were compared with x2 test and two-sample t test.After assignment of significant factors and groups,correlations between each factor and group were analyzed with uni-and multivariate analyses,and then the risk factors were identified finally with logistic regression analysis.Results Significant difference among factors of tumor size ((36.1±19.7) mm vs (49.3±24.4) mm),SUVmax(8.81±6.23 vs 11.21±4.43) and differentiation grades (high:3 vs 0; moderate:74 vs 11; poor:65 vs 24) were observed between non-N2+ group and N2+ group (t =-2.969,-2.633,x2 =6.143,all P＜0.05).Besides,the univariate analysis showed significant correlations between tumor size,SUVmax,differentiation grade and N2 status (r=0.201,0.245,0.185,all P＜0.05).However,multivariate logistic regression revealed that only SUVmax had a predictive value (β=0.546,P＜0.01).The incidence of N2 metastasis went up along with the increase of SUVmax.There was no N2 metastasis in the patients with SUVmax ≤2.5,and the incidence rate of metastasis increased to 0.29 in those with SUVmax＞7.5.Conclusion SUVmax may be an independent risk factor to predict N2 metastasis in NSCLC patients.