The American Academy of Pediatrics Practice Parameter, The Neurodiagnostic Evaluation of a Child with a First Simple Febrile Seizure, does not recommend serum electrolytes be obtained routinely. Two reports from Europe, however, identified relative hyponatremia as a risk factor for febrile seizure recurrence within 24 hours. If confirmed, this would have potential impact on the approach to these patients. The charts of 175 sequential children ages 6 months to 5 years who presented to the Children's Hospital of Buffalo emergency room in 1999 with generalized seizures lasting less than 15 minutes were retrospectively reviewed. One hundred thirty-six patients were febrile and 39 (control group) were afebrile. Serum electrolytes were performed on all. The mean serum sodium for the 27 children with more than 1 febrile seizure in 24 hours (135.48 mmol/L) did not differ from those 109 febrile children whose seizures did not recur within 24 hours (135.56 mmol/L). Of interest, the mean serum sodium for the 109 children with simple febrile seizures, as well as those with recurrent "simple" febrile seizures were significantly lower than the control group of children with afebrile seizures. These findings reaffirm the recommendation of the American Academy of Pediatrics Practice Parameter to not routinely obtain electrolytes.