A prospective epidemiological study of the incidence of simple febrile convulsions (FC) was performed in a northern Swedish county. The yearly incidence was 700/100 000. The children with FC were re-examined three years later. The pre- and perinatal complications were significantly more common in the group of children with FC than in a randomly collected group of controls. The value of an extensive investigation program is discussed. Between six months and five years of age the children with FC can be separated from those with other cerebral diseases causing epileptic seizures by recording a thorough history followed by a somatic and neurological physical examination and a determination of acute blood glucose. In children less than six months of age and in children in which meningitis or encephalitis cannot be ruled out, a lumbar puncture and a blood culture should be performed. If the onset of the convulsion has been after five years of age, if the seizures are partial or have a duration of more than 30 minutes, or if signs of cerebral disease are found, the examination should be supplemented with EEG and relevant investigations. There is no need for an extensive routine program of investigations in the care of children with FC.