Mood disorders, particularly depression, now represent a major world health problem which will most likely continue increasing. From a clinical standpoint, the synthesis of new antidepressant agents of various chemical structures and the advent of the thymoregulators (lithium salts) has allowed a more flexible, better individualized, therapeutic approach to the affective disorders. However, the widespread use by general practitioners of the antidepressants, alone or in combination with other psychotropic drugs, often with mitigated success, brings to psychiatric consultation patients whose symptomatology has become less characteristics, is more difficult to identify rapidly, requiring thus greater diagnositc refinement. Moreover, greater attention is currently given to depressive affects that can occur during organic illnesses or at various periods of life, particularly at senescence. Besides sustained concerns concerning suicide, the attitude of man confronted with his death arouses great interest and a depressive phase constitutes one of the steps towards this ending. Finally, during the last two decades, some psychoanalysts have reexamined the psychodynamic concepts of mood disorders, whereas from behavioral and cognitive theories new techniques of treatment of depression have emerged. In brief, if no revolution has occurred, there has been evolution. Mood disorders and their approach have known modifications and some concepts pertinent to this are considered here from various angles, particularly from the clinical (association with organic illnesses, with respect to death), therapeutic (psychopharmacological, behavioral and cognitive therapies), sociological (including suicide) and psychoanalytic viewpoints.