The alleged incidence of addiction to fruit machine gambling among children in the U.K. has highlighted the need for a measure to define and count pathological gambling in children. The DSM-IV criteria, which are being refined to diagnose pathological gambling in adults, was adapted for use with pre-adult gamblers. The resulting DSM-IV-J criteria were tested using a questionnaire survey on a sample of 467 schoolchildren aged between 11 and 16 years. Those children who were defined as probable pathological gamblers by the DSM-IV-J index were significantly more likely to be involved in behaviours hitherto associated with dependency, than were the control group. DSM-IV-J appears to be a major advance in the discrimination of pathological gambling in children.