The paper presents study of self-aggression in adolescents, describing gender differences in frequency, age dynamics, risk factors, conditions and nature of self-aggression. Factors leading to suicide attempts in adolescents of either sex tend to be similar. Suicidal behaviour in boys correlated with aggressive fantasizing, signs of residual organic injury of the brain, deviations in sex-role orientations, suffering from physical violence in childhood. Suicidal attempts in girls were more associated with taking psycho-active drugs, committing criminal offences, experiencing sexual violence and mental disorders, mostly emotional.