Depressed patients show a variety of alterations in hypothalamic-pituitary-adrenocortical (HPA) system regulation which is reflected by increased pituitary-adrenocortical hormone secretion at baseline and a number of aberrant neuroendocrine function tests. The latter include the combined dexamethasone (DEX) suppression/corticotropin-releasing hormone (CRH) challenge test, in which CRH was able to override DEX induced suppression of ACTH and cortisol secretion. Whereas the abnormal HPA activation in these patients improved in parallel with clinical remission, persistent HPA dysregulation was associated with an increased risk of relapse. Moreover, healthy subjects at high genetic risk for depression also showed this phenomenon as a trait marker. In consequence, it has been concluded that HPA alteration and development as well as course of depression may be causally related. As evidenced from clinical and preclinical studies, underlying mechanisms of these abnormalities involve impairment of central corticosteroid receptor function which leads to enhanced activity of hypothalamic neurons synthesising and releasing vasopressin and CRH. These neuropeptides mediate not only neuroendocrine but also behavioural effects. Recent research provided evidence that CRH can induce depression-like symptoms in animals and that these signs are mediated through the CRH1 receptor subtype. Hence, therapeutical application of new compounds acting more specifically on the HPA system such as CRH1 receptor antagonists appear to be a promising approach for future treatment options of depression. In conclusion, research in neuroendocrinology provided new insights into the underlying pathophysiology of depression and, in consequence, may lead to the development of new therapeutic tools.