The prevalence and clinical features of migraine headache and abdominal migraine were studied in the well defined population of Aberdeen schoolchildren. Ten per cent of all children (2165) aged 5-15 years were given a questionnaire inquiring, among other symptoms, about the history of headache and abdominal pain over the past year. A total of 1754 children (81%) responded. Children with at least two episodes of severe headache and/or sever abdominal pain, attributed by the parents either to unknown causes or to migraine, were invited to attend for clinical interview and examination. After interview, 159 children fulfilled the International Headache Society's criteria for the diagnosis of migraine and 58 children had abdominal migraine giving estimated prevalence rates of 10.6% and 4.1% respectively. Children with abdominal migraine had demographic and social characteristics similar to those of children with migraine. They also had similar patterns of associated recurrent painful conditions, trigger and relieving factors, and associated symptoms during attacks. The similarities between the two conditions are so close as to suggest that they have a common pathogenesis.