Recent advancements in the field of imaging, particularly magnetic resonance imaging, have improved the way peripheral nerve tumors are diagnosed, monitored, and treated both medically and surgically. When combined with the all-important clinical evaluation and electrodiagnostic studies, imaging permits a clinician to accomplish the following: identify the size, shape, location, and distribution of mass lesions; infer the risks in resecting a mass lesion by displaying its relationship to nearby nerve fascicles; determine growth rates when serial imaging studies are available; suggest the nature of the pathological entity; and visualize muscle denervation associated with nerve damage. The authors describe some of the commonly used imaging modalities and discuss their use in evaluating and treating peripheral nerve tumors and other mass lesions.