Zinc modulates the activity of glutamic acid decarboxylase, the rate limiting enzyme in the synthesis of gamma-aminobutyric acid (GABA), which is a major inhibitory neurotransmitter. Low cerebrospinal fluid GABA values have been reported in association with several seizure disorders, including febrile convulsions. It is also known that fever and/or infections may cause a reduction in serum zinc concentrations. In this study the hypothesis that febrile convulsions are related to low cerebrospinal fluid zinc was tested. Cerebrospinal fluid zinc concentrations were measured in 66 febrile children: 32 with febrile convulsions, 18 with fever but without convulsions, and 16 with aseptic (viral) meningitis. There was no statistically significant difference in the cerebrospinal fluid zinc between the three groups of children, and the mean concentration was 26.2 micrograms/l. No significant relationship was found between either age, gender, maximal temperature, type of infection, or time of performance of the lumbar puncture and cerebrospinal fluid zinc concentration. These results do not support the hypothesis that febrile convulsions are related to reduced cerebrospinal fluid zinc concentrations.