Schwannomatosis is characterized by the development of multiple schwannomas without evidence of vestibular tumors. Segmental schwannomatosis is defined as being limited to 1 limb or 5 or fewer contiguous segments of the spine. We report a case of a 38-year-old male with multiple, painful masses of the right upper extremity with associated numbness and paresthesia in the ulnar and radial nerve distribution. An open, microsurgical approach provided definitive diagnosis and treatment. Twenty-one cases of segmental schwannomatosis of the upper extremity have been reported in the literature, making this case the 22nd. It is 1 of 5 cases of segmental schwannomatosis to have simultaneous tumors in the forearm and hand. We are the first to report multiple schwannomas of the ulnar and ulnar sensory nerve and the second to report multiple schwannomas of the radial sensory nerve. We additionally review the literature regarding pathogenesis, diagnosis, and treatment of this uncommon tumor.