Mediastinal masses are relatively uncommon, yet include a large variety of entities. Some tumors can be diagnosed with confidence based on imaging alone; others when a typical appearance is combined with the right clinical presentation. A structured approach for radiologists is presented to facilitate evaluation of patients with anterior mediastinal tumors. The approach focuses first on the more common tumors and on imaging features that strongly suggest a particular diagnosis. Discussion with the clinician can be very helpful in formulating a presumptive diagnosis. This article also discusses that confirmatory imaging or biopsy tests are most beneficial in particular situations.