Evaluation of the brachial plexus is a clinical chal-lenge. Physical examination has traditionally been a mainstay in evaluating and localizing pathology involving the brachial plexus. Physical examination is especially difficult in patients with scarring and fibrosis secondary to surgery or irradiation. Electrophysiologic studies may be used to detect abnormalities in nerve conduction, but are poor for localizing a lesion. "nMRI has become increasingly important in the evaluation of brachial plexus pathology, as the technology and resolution has improved. Correlation of imaging results with electrophysiologic findings increases the overall specificity and sensitivity. CT has increased sensitivity for depicting extrinsic masses that com-press the nerves; however, it offers poor soft tissue contrast to directly evaluate the nerves."nWith the advent of MRI, nerves that compose the brachial plexus can now be directly evaluated. Intrinsic and extrinsic pathology may be evaluated. Exact anatomic components of the brachial plexus, such as the roots, trunks, divisions, and cords may be identified. MRI has the additional benefit of multiplanar imaging and increased soft tissue contrast. The tissue resolution of MRI is constantly improving with new pulse sequences and coil designs."nWith radiography and CT, changes in the shape or position of the brachial plexus were used to assess the pathology. With MRI, the nerve can be directly visualized and evaluated for pathology. MRI sequences such as fat-saturated T2-weighted spin-echo, short-tau inversion recovery (STIR), and gadolinium-enhanced T1-weighted spin-echo sequences help in depicting subtle changes in the signal intensity of the nerves or enhancement and aid in refining the differential diagnosis. In addition, maximum intensity projections can make localization and visualization of the pathology most understandable for referring clinicians and surgeons.