The mediastinum is a complex anatomical space from which a variety of benign and malignant pathological processes arise. Thymomas, neurogenic tumors and benign cysts account for 60% of mediastinal masses. The location and imaging characteristics of the mass are critical to narrowing the differential diagnosis. The new mediastinal division scheme developed by ITMIG (International Thymic Malignancy Interest Group) into prevascular, visceral and paravertebral compartments enables a more precise identification of mediastinal masses using cross-sectional imaging methods. The first step in the assessment of a mediastinal mass is a chest radiograph, however additional imaging methods are required for a more precise characterization. The gold standard in the diagnosis of mediastinal masses is multi-slice computerized tomography (MSCT), which provides detailed insight into the location and size of the tumor, its connection to adjacent structures and tissue characteristics. If the diagnosis is uncertain, magnetic resonance imaging (MRI) provides further insight into the characterization of the mass due to its superior soft tissue contrast resolution, along with better insight into invasion of surrounding tissue, pathological lymph nodes and metastases. Advanced MRI techniques such as chemical-shift MRI, diffusion weighted imaging and dynamic contrast enhanced imaging can be used in certain cases to further evaluate mediastinal masses.