Aims To provide empirical data-driven identification of a group of addicted online gamers. Design Repeated cross-sectional survey study, comprising a longitudinal cohort, conducted in 2008 and 2009. Setting Secondary schools in the Netherlands. Participants Two large samples of Dutch schoolchildren (aged 13-16 years). Measurements Compulsive internet use scale, weekly hours of online gaming and psychosocial variables. Findings This study confirms the existence of a small group of addicted online gamers (3%), representing about 1.5% of all children aged 13-16 years in the Netherlands. Although these gamers report addiction-like problems, relationships with decreased psychosocial health were less evident. Conclusions The identification of a small group of addicted online gamers supports efforts to develop and validate questionnaire scales aimed at measuring the phenomenon of online video game addiction. The findings contribute to the discussion on the inclusion of non-substance addictions in the proposed unified concept of 'Addiction and Related Disorders' for the DSM-V by providing indirect identification and validation of a group of suspected online video game addicts.