The etiology of drug addiction, a central nervous system (CNS) disease, is not fully known. This complex problem is believed to be connected with concurrently affecting genetic, psychological and environmental factors. The development of addiction is connected with CNS reinforcement system and dopaminergic neurotransmission. Molecular processes are postulated to be of universal character and allow to presume a similar mechanism of dependence for both ethanol and other substances. Therefore, elements of dopaminergic transmission become excellent candidates for the examination of genetic influence on the development of addiction. A relationship between alcoholic disease and the presence of TaqIA1 and DRD2 alleles permits to initiate another investigation of gene-coding DRD2 dopamine receptor. The latest results indicate the importance of brain-derived neurotrophic factor (BDNF) in the regulation of dopaminergic route. The purpose of this research was to reveal the relationship between the Val66Met BDNF gene polymorphism and dependence of psychoactive agent. The examinations were performed with the Local Research Ethics Committee approval and patient's consent. The study group consisted of 100 patients (88 men and 12 women) aged 18-52 years, qualified for research program according to the International Classification of Diseases, Tenth Revision (ICD-10) requirements, medical examination and detailed questionnaire.