Stage III non-small cell lung cancer (NSCLC) is a highly heterogeneous subtype of lung cancer. There are still no widely accepted prognostic parameters for stage III NSCLC. In this study, we evaluated the prognostic value of the standardized uptake value (SUV) max ratio of primary tumor to lymph node (T/N SUV max) and its correlation with various hematological parameters.Patient data were reviewed from the hospital database retrospectively. The T/N SUV max ratio was calculated by dividing the SUV max of the primary tumor by the maximal SUV max of the lymph node. The cut-off value for T/N SUV max ratio was determined by receiver operating characteristic analysis. Survival analysis was performed by Kaplan-Meier method with the Long-rank test. P value < .05 was considered statistically significant.A total of 52 patients were included in this study. The optimal cut-off value for T/N SUV max was 1.96 (area under the curve: 0.74; 72.7% sensitivity and 73.7% specificity). Patients with T/N SUV max ≤1.96 were defined as high risk patients and those with >1.96 were defined as low risk patients. The median event (recurrence or progression) free survival was 24.3 months (95% confidence interval: 12.0-36.6) for low risk patients, and 9.2 months (95% confidence interval: 6.1-12.4) for high risk patients (P = .0015). There was an inverse correlation between T/N SUV max and hemoglobin concentration and mean corpuscular volume (rho: -0.349, P = .011; rho: -0.312, P = .025, respectively).Low risk patients had a more favorable prognosis compared to high risk patients. We demonstrated that T/N SUV max can be of prognostic value in stage III NSCLC. T/N SUV max correlated only with hemoglobin and mean corpuscular volume.