This chapter covers the pituitary gland. It starts with the anatomy and physiology, then moves on to imaging, and pituitary function. It then covers common tests, including ITT, glucagon, ACTH stimulation, arginine, clomiphene, hCG, and TRH. It then begins to cover disorders of pituitary function, with treatment, hormone replacement, and investigation all included. Pituitary tumours are described, along with investigation, diagnosis, and treatment. Other disorders, including Cushing’s disease, cysts, inflammatory conditions are all included. Complications from other conditions are also described.