This article presents the results of an empirical study on the role of hostility in the etiopathogenesis of mental illness such as schizophrenia, schizoaffective and affective disorders. The relationship of the general level of hostility and enmity with the qualitative aspects of the objective characteristics of mental illness (duration and nosology) is described in the following article. The sample consists of 161 people, of which the clinical group consisted of 81 patients who are hospitalized in the 4th department of the clinic affective pathology. Comparison was made with a control group of healthy persons, which included 80 men who do not suffer from mental and neurological disorders. The study used the following methods: semantic differential (modification by Ohmatovskaya A.V.), World assumptions scale, Constructive Thinking Index (CTI), Cook-Medley Hostility scale, Buss-Perry Aggression Questionnaire, Wechsler memory scale, Wagner’s “Hand-test” (modification by A.V. Gerasimov). It was found that mentally ill patients were showing significantly higher quantitative measures of hostility, compared with the norm. Psychopathological marked qualitative specificity of hostility expressed in suspicion, ambivalence, extrapunitive and generalized hostility. According to the results, hostility has not direct connection with the nosology specific of the mental disorders, and does not depend on the patient’s age and duration of disease.