The author presents his investigations of the nosologic and hereditary features of forty-two cases of anxiety and agitated psychoses, chiefly depressions, in both men and women. His conception is a modification of the classification of Kraepelin, which separated the involutional melancholias from the manic-depressive cases. Leonhard concludes from a study of his material that there are periodic anxiety and agitated depressions occurring in younger persons, which are "idiopathic" and should not be included among the manic-depressive group. He finds a strong hereditary basis for these psychoses and considers them identical with the more typical involutional agitated depressions, because of their symptomatologic and hereditary similarities. The case material is presented with a brief clinical description of each psychotic episode and a brief description of psychopathic members of the family. The discussion concerns itself exclusively with phenomenologic and hereditary data, completely disregarding the personality, experiential and biographic features and their dynamic implications.