It is proposed to select two groups of mental patients, each member of each group to be matched as nearly as possible with respect to age, sex, intellect, diagnosis, socio-economic status, etc., with a member of a second group. Both groups are to receive identical treatment, except that one group, the therapeutic, is to receive intensive psychoanalytic therapy. The other or control group is to receive little or no psychotherapy and no psychoanalytic therapy. Written statements of the condition of all patients at the beginning of the experiment, together with the probable prognosis, should be made. All patients should be followed for several years until the outcome of the therapy or lack of therapy is clear. From this study we should gain information concerning the diagnostic type, age, sex, intellectual status, etc., for which psychoanalysis is indicated or contra-indicated. The frequency of success and failure of the psychoanalytic therapy could be stated. A basis for the relative worth-whileness of the use of psychoanalytic therapy and methods in the mental hospitals could be made.