Depression is one of the most common psychiatric disorders. For a long time, clinicians suspected a causal link between depression and the endocrine system. The most frequently occurring endocrine abnormality in depressed subjects is hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. CRH and AVP are likely to play a substantial role in the pathophysiology of this disorder, and their receptors appear to be a specific target for future antidepressant drugs. Depression also affects the hypothalamic-pituitary-GH (HPGH) and -thyroid (HPT) axes. Alterations in the reproductive system may also play a role in the pathology of depression. In addition, there is increasing evidence that leptin and neurosteroids, such as DHEA, are implicated in mood disorders.