Central diabetes insipidus (CDI) is a rare condition resulting from arginine vasopressin deficiency and characterized by marked polyuria and polydipsia. This chapter provides an introduction to CDI and discusses its causes, including neoplasia and trauma. It also describes the clinical features of CDI as well as potential neurological signs and concurrent endocrinopathies. The diagnosis of CDI is discussed, including the use of urinalysis, water deprivation tests and measurement of plasma arginine vasopressin. The importance of treating underlying pathology is highlighted, though treatment options such as desmopressin therapy are outlined. The chapter also mentions other types of diabetes insipidus and differential diagnoses for CDI.