\s=b\ Febrile seizures are a common pediatric problem, yet there is a great deal of disagreement about the appropriate diagnostic evaluation of a child with this disorder. We reviewed the routine diagnostic tests performed on 100 consecutive children admitted with their first "simple" febrile seizure. The studies performed included lumbar puncture, measurement of blood glucose, serum calcium, serum electrolytes, and BUN levels, blood cell count, urinalysis, skull roentgenograms, and EEG. Though resulting in a significant expense, these routine investigations proved to be of little diagnostic value. Based on this experience and a review of the current literature, we concluded that diagnostic procedures should be performed only when specifically called for by the patient's condition or medical history. (Am J Dis Child 1981;135:431-433) Approximately 3% to 5% of all chil-11 dren will have experienced at least one febrile seizure by the time they enter school.'1 More than 80% of these febrile seizures may be classi¬ fied as "simple": a single, isolated seizure that occurs in a febrile child between 1 month and 7 years of age with no sign of acute neurological disease, lasting 15 minutes or less, and without focal features.' As shown by a recent nationwide survey of pediatricians, there is a great deal of disagreement about the appropriate diagnostic evaluation of children with first febrile seizures.4 Some have recommended that lumbar punctures be performed routinely, along with determinations of blood glucose, serum calcium and phospho¬ rous, electrolyte, and BUN levels. Additionally, blood cell count, urinalysis, skull roentgenograms, and EEG are often routinely performed/'" Re¬ cently, however, the value of these investigations has been seriously questioned.7 * Much of this confusion is attributable to the lack of informa¬ tion on the yield of commonly per¬ formed diagnostic procedures, and perhaps to the failure to distinguish between simple and complex febrile seizures. Lumbar punctures are often per¬ formed on children with febrile sei¬ zures to exclude meningitis as the cause of the seizure. Thirteen percent to 18% of the children with meningitis may initially appear with a febrile seizure, and approximately 40% of these children may have no clinical signs of meningeal irritation." "' The majority of these children without clinical evidence of meningitis were, however, younger than 2 years of age, and a careful differentiation of simple and complex febrile seizures was not attempted by the authors of these reports. Many believe that a history of previous febrile seizures or the iden¬ tification of a potential source of fe¬ ver outside of the CNS preclude the necessity for a lumbar puncture in a child with a febrile seizure. However, a significant number of children with febrile seizures who are diagnosed as having meningitis have a history of previous febrile seizures or a potential source of fever outside of the CNS.!M" Wolf et al reviewed 308 lumbar punctures performed on children with their first febrile...