This paper deals with a difficult subject in psychiatric and psychotherapeutic practice: the acting-out patient. There are dubious results provided by present therapeutic approaches, even taking in account the aid of modern psychotherapies and classic therapeutic community principles. The International Classification of Diseases (LCD.) diagnoses of acting-out patients vary: they are neurotics (LCD. 300), they show personality disorders (LCD. 301), they are psychotics (LCD. 295 to 299), and they often carry with them severe secondary symptoms which constitutes a second diagnose: alcoholism and addictions (LCD. 303 and 304, respectively). Through the psychoanalytical approach, the author proposes a focal brief psychotherapy with the aid of a counter acting-out therapeutic environment, provided by a closed-door mental hospital. By the use of some criteria of cure, which are internally coherent with the therapeutic proposal, it is verified in which extent 36 in-patients could meet those criteria when submitted to the method. An algebric score was given to each patient. This score is a number which expresses the patient's clinical performance during the hospitalization and during the follow-up discharge time (Mean time of follow-up obtained: 21 months). Two groups emerged from the original 36 patients group: a favorable outcome group, composed by 36% of patients, and an unfavorable group. The study comprises a statistical evaluation of this result, by comparing it with the results obtained with a matched, non submitted to the method, 41 - patient group. The value of the statistical test used, the chi square, was non-significant, at a level of 0.01. There was made a further examination of the proportions obtained when the two groups were divided by each diagnoses. There is a strong evidence that this variable had an influence in the overall results. The method seems to be of some utility when applied to acting-out neurotics 'and acting-out psychotics, but show no efficacy when applied to acting-out personality disorders. No statistical test was used in the analysis of each pathology, because there were no sufficient number of patients in the control group. The study provides a theoretical frame-work and a critical analysis on statistical conclusions,