The author tries to summarize the studies of Kleist and his collaborators concerning the degeneration psychoses or phasophrenias, group constituted by those benign, atypical, phasic and cyclical psychoses, presenting a rich and varied symptomatology due to their mixed and attenuated heredological characters. At first these disease were related to the great endogenous groups - maniacs-depressive psychosis, paranoia and epilepsy - and were classified as collaterals groups for practical and historical reasons as pointed Kleist, who postulated that their benign characteristics was due to a degeneration of the disease's genetical morbidity. The author stress the importance in identifying these psychoses since they represent about 25% of the endogenous mental diseases. Furthemore, as they recover without defect, in accordance with their benign nature, they should not be mistaken with schizophrenia, as often occurs. Their diagnosis also would help in avoiding the exaggerations on the efficacity of new therapeutical drugs, that appear day by day in the psychiatric field.