There exists an extensive body of literature examining the value of intraoperative nerve monitoring (IONM) of the recurrent laryngeal nerve during thyroid and parathyroid surgery. These studies have advanced the understanding of electrophysiologic nerve monitoring and have culminated in the publication of international guideline statements on standards of IONM as well as use of IONM in intraoperative decision-making. This chapter reviews the value of intraoperative nerve monitoring with a specific interest in its application regarding parathyroid surgery. The rationale for monitoring is addressed in the context of the unique circumstances of parathyroid surgery. Furthermore, the expected value of nerve monitoring for the intraoperative decision process, techniques, and equipment, as well as contemporary trends and future directions of IONM are covered.