In this article deliberate self-injury is described as a distinct phenomenon that usually manifests itself in a definite pattern. A definition is formulated and the term `deliberate self-injury' is accounted for. Following a description of the diverse forms, deliberate self-injury is delimited with regard to other forms of self-destructive behaviour, such as suicide-attempts. The unequivocal description of the course of the act, the coinciding emotions and the related problem areas support the conclusion that deliberate self-injury is to be considered a distinct phenomenon. Finally, prevalence of deliberate self-injury is portrayed with special emphasis on the factors age and sex.