The brachial plexus disease is anatomically complex. Moreover, each patient’s neurological condition is highly variable and the decision-making during surgery is challenging. Thus, the surgical approach should be individualized. Sufficient evaluation, including preoperative electrophysiological study and radiological examination is essential; however, these evaluations have some limitations. Intraoperative neurophysiological monitoring is introduced in brachial plexus surgeries and offers additional benefits. This technique is not different from the intraoperative neurophysiological monitoring technique for peripheral nerve surgeries; however, special monitoring systems are required in brachial plexus surgeries. In traumatic brachial plexus injuries, differentiating the preganglionic or postganglionic lesions can provide decisive information in determining the surgical method. Although there is a lack of clinical evidence on the benefits of intraoperative neurophysiological monitoring in the surgery for brachial plexus disease, it is necessary to investigate the benefits through a well-designed prospective study based on a detailed evaluation of neurological deficits before and after surgeries.