Tumors of the mediastinum represent a wide diversity of disease states. CT scan plays important role in improving the accuracy of diagnosing these masses by narrowing the differential diagnosis through delineating anatomic location, extent of disease, tissue invasion, and tissue density. This CT based study reviewed types of mediastinal masses and their percentage among Sudanese patients and the role of CT scan in the evaluation of these masses and limiting their differential diagnosis. The net sample size in this study was 113 patients, only 64 patient were of significant CT findings while 49 patients were non-significant. Classifying mediastinal masses into benign and malignant (72%) of the whole mediastinal masses were benign and the other (28%) were malignant, among malignant mediastinal masses Bronchogenic carcinoma was found the commonest, and thymoma was found as the commonest among benign mediastinal masses. It has been found that CT scan is to a far extent considered a reliable method of evaluating mediastinal tumors, moreover it is sufficient for pre-operative evaluation.