In this study we evaluate the incidence and clinical characteristics of headache which arise 12-18 months after a cranial trauma in a pediatric age group of subjects. We contacted 217 individuals who had been hospitalized for head injury to return for check-up; of the 138 who responded, there were 86 males and 52 females (mean 9.2 years). The responders were given a complete physical and neurological examination and, in the presence of at least one parent, asked to fill out a headache questionnaire. Twenty-nine per cent suffered from headache, and in 6.5% the headache was migrainous in nature. The 138 patients were split up into three sub-classes in accordance with the nature of the trauma and two sub-classes in accordance with the presence or absence of fractures. The results were then compared with those obtained from a control population (246 patients with a mean age of 8.8 years). An increased headache frequency was found in those patients with average to severe trauma. We conclude that cranial trauma is not likely to be followed by headache unless accompanied by loss of consciousness and/or focal neurological signs.