Abstract: Objective :To evaluate the role of spiral Computed Tomography (CT) of mediastinallymph nodes in staging of non-small cell lung carcinoma (NSCLC). Methods :The staging of NSCLCbased on imaging of mediastinal lymph nodes of 89 patients diagnosed as NSCLC histopathologically byCT was conducted, and the corresponding pathologic staging was compared. Results :The total sensi-tivity, specificity, positive and negative predictive value and the accuracy of mediastinal lymph nodestaging by CT scan was 58.9%, 70%, 60.5%, 68.6% and 65.2%, respectively. The accuracy and speci-ficity of CT was relatively low in staging of the 4R, 5, 6 and 7 lymph node groups. False-negative and false-positive rates were relatively high in 4R and 7 lymph node groups. Conclusion :CT of mediasti-nal lymph nodes plays an important role in staging NSCLC, however there is a small problem withfalse- negative and false- positives. Spiral CT should be combined with the results of other investiga-tions to ensure a more accurate staging.