<p>The importance of studying the biological basis of suicidal behavior (SB) is beyond doubt, as suicidal behavior contradicts the basic physiological foundations of the instincts of survival and self-preservation. Research into this issue is of particular importance in adolescents, as this is the age group in which the frequency of SB increases sharply. This leads to the need to search for reliable biomarkers of SB for valid assessment of suicide risk and for developing approaches to its prevention. This review reflects results from modern biological research in the main areas of genetics, neurochemistry, neuroimmunology, and neuroimaging and reflects the most significant abnormalities associated with SB. Comprehensive research into anomalies in all the above areas will allow a combination of the most significant of them to be identified. In addition, knowledge of different pathogenetic pathways of SB formation will lead to the development of new effective approaches to prevention.</p>