Discriminated psychiatric patients who refuse and/or terminate treatment prematurely from those patients who accept and complete a behavioral treatment designed for them. The current study examined three groups of non-medicated psychiatric patients. The three groups consisted of patients who: (1) refused treatment; (2) accepted treatment but terminated prematurely; and (3) accepted and completed treatment. The experimental procedures consisted of psychometric tests and the monitoring of levels of physiological activity during relaxation and task performance. The results indicated that treatment predictive accuracy was possible among non-medicated psychiatric patients. Psychopathic and neurotic personality determinants were significant predictors among the three groups. Furthermore, digital pulse volume, minimum pulse during a relaxation phase, and an individually corrected performance skin conductance coefficient were three of six significant physiological discriminative predictive characteristics. A total of 15 criteria provided a clinically sensible and practical means of approaching the problem of treatment prognosis for psychiatric patients.