Headache is one of the commonest conditions to affect children and adolescents in industrialised countries. Studies indicate a prevalence of 8-60%. In over 40% of migraineurs the condition begins before 18 years of age. For clinical researchers, headache in the young is of interest because its causes are easier to investigate than in older people, as the clinical history is brief, the condition has had no time to become chronic, and it is not accompanied by changes in pain neuromodulation and neurotransmission, or the development of a chronic pain/stress-related personality that is common in adults with longstanding headache. The wide variation in reported headache prevalence in young people may be ascribed to lack of representativity of studies and vagueness of diagnostic criteria in studies performed before 1988. The publication of the International Headache Society IHS classification in 1988 for the first time made it possible to accurately diagnose the various headache forms. The diagnostic criteria for adults were adopted for use in young patients. Since that time a burgeoning number of studies on headache in young people have been published.