Self-injury is a common phenomenon among adolescents and young adults, however its prevalence in clinical population is estimated at 40–80%, especially in regard to patients during puberty. Symptoms usually appear between 12th and 14th year of age, and their average duration is approx. 2 years. According to accepted sociocultural norms self-injury can be regarded as a normal behavior. Nevertheless, the prevalence of body art phenomenon in Western culture including professional tattooing, piercing, scarification, burning tattoos and other body modification typical for tribal cultures, has forced the need to redefine the boundaries for normative behavior. Introduction of a separate nosological unit of Non-Suicidal Self Injury in the fifth edition of DSM classification proves the validity of discussion, being hold for many years, regarding classification and understanding of the underlying mechanisms of self-harm. The aim of our study was to present the current state of knowledge regarding self-harm, with an emphasis on issues devoted to their placement in newest mental disorders classifications and mechanisms responsible for their development and maintenance. Databases such as: PubMed, EBSCO (medical and psychological resources) and WEB OF SCIENCE (years 1990–2016) have been screened for the following key words: self-injury, self-harm, self-mutilation, suicide, deliberate self-harm, affect regulation, NSSI, DSH, personality disorders, suicide attempt, neurobiology self-harm, DSM-5, adolescent, adults, stress coping styles, self-mutilation – children, adolescents and adults-prevalence. The analysis indicated 110 articles and 3 textbooks. We have used the following criteria: (1) for the articles presenting the latest research on risk factors for self-harm we have used the criterion of the study group number (>30 people) and meta-analyses have been included, (2) for theories explaining the mechanisms of self-harm criterion of empirical review of the assumptions and the number of the published studies that verify the theory has been applied.