SUMMARY Twenty-nine infants and children with short (<30 minutes) first febrile convulsions were studied between 3 and 22 hours after convulsive episodes. Arterial and CSF acid-base variables, lactate and pyruvate concentrations, and lactate/pyruvate ratios were measured. Biochemical signs of cerebral hypoxia were found in only 2 patients, one of whom had short, repeated convulsions. Our findings indicate that hypoxic damage is unlikely to result from a short-duration febrile convulsion.Febrile convulsions affect some 6 % of young children mainly between the ages of 6 months and 4 years. The long-term prognosis for such patients is usually good, though a small number, at most 5-10%, ultimately develop chronic epilepsy (see review by Lennox-Buchthal, 1973). Moreover, when