The diagnostic criteria of restless legs syndrome were defined in 1995 by the International Restless Legs Syndrome Study Group (IRLSSG). In light of the latest scientific evidence and increasing clinical experience, the diagnostic criteria were revised in a consensus workshop. Participants of the workshop considered the development of new diagnostic criteria especially important for the following subgroups: (1) for children and (2) for the cognitively impaired elderly. The common characteristic of both groups lies in their difficulty in expressing subjective symptoms adequately. This considerably impedes the diagnosis of restless legs syndrome. In 2002, a proposal for diagnostic criteria of restless legs syndrome in childhood was formulated by members of the study groups "Movement Disorders and Sleep" and "Paediatrics" of the German Sleep Society. The proposal was partially incorporated into the diagnostic criteria for restless legs syndrome in childhood suggested by the IRLSSG. The current criteria are recommendations to enhance further research and must be validated by clinical studies. The following article gives an overview of published studies on restless legs syndrome in childhood, reviews the proposals for diagnostic criteria, and summarizes the peculiarities to be considered in diagnosing restless legs syndrome in children.