Twenty infants and children with febrile convulsions (FC) have been studied with analysis of the CSF lactate and pyruvate concentrations and lactate/pyruvate ratios performed between 10 minutes and 9.5 hours after a sustained FC episode. No biochemical signs of cerebral hypoxia could be found after shortlasting FC. The findings indicate that hypoxic brain damage as a consequence of shortlasting FC is very unlikely.