Ultrasound, either as a single modality or in conjunction with functional imaging, is an indispensable tool in the evaluation and management of parathyroid disease. Accurate preoperative localization of target glands is critical to anticipating ectopic parathyroid tissue and ensuring surgical success. Ultrasound may also be used to facilitate diagnostic and therapeutic interventions for hyperparathyroidism in select patients. This chapter comprehensively reviews the preoperative ultrasound assessment of parathyroid glands, including review of scanning technique, sonographic characteristics of abnormal glands, and ultrasound-guided interventions. Ultrasonography of normal parathyroid glands will also be discussed.