Intraneural perineurioma is an uncommon benign tumor of the perineurium of peripheral nerve sheaths occurring primarily in adolescents or young adults. MRI is a valuable tool in suggesting this diagnosis and in surgical planning. We report an 18-year old female with progressive right-hand weakness, numbness, and severe atrophic changes of the hand secondary to an intraneural perineurioma involving the right brachial plexus, in whom the initial diagnosis was suggested by MRI.