The work is devoted to a topical medical and social problem - exogenous-organic diseases of the brain in adolescents. Based on a clinical and epidemiological study conducted at the Department of Psychiatry and Narcology, Altai State Medical University, the monograph presents data on the prevalence of exogenous-organic mental disorders among adolescents who applied and did not apply for psychiatric care. The causes of development of organic lesions of the brain are analyzed in detail and the clinical characteristics of these disorders are given, an emphasis is placed on the social significance of exogenous-organic pathology - its impact on training and professional self-determination of adolescents, the principles of diagnosis of exogenous-organic diseases of the brain are presented in detail and the issues of their therapy and prevention are highlighted. The book is intended for psychiatrists, medical psychologists, teachers and other professionals working in the field of mental held of mental health care.