The parathyroid glands are endocrine glands within the neck whose function is to control serum calcium levels within the body through the excretion of parathyroid hormone (PTH). Hyperparathyroidism (HPT) is characterised by increased levels of PTH resulting in hypercalcaemia, urinary tract calculi, osteoporosis, musculoskeletal pain, change in mood and fatigue. It may be primary, secondary and tertiary depending on the underlying cause. Endocrine surgeons are predominantly involved in the management of primary HPT where the underlying pathology is frequently a parathyroid adenoma, but there is debate regarding the role of surgery in secondary and tertiary HPT. This chapter sets out to describe the embryology, anatomy and function of the parathyroid glands in order to facilitate an understanding of HPT including its aetiology, presentation, evaluation and management.