Cerebrospinal fluid (CSF) concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA) and probenecid were examined in 14 children with epilepsy (ages 6 months to 17 years) and 17 controls (ages 14 months to 16 years). The concentrations of amine metabolites were significantly correlated with probenecid concentrations in both groups of children. Cerebrospinal fluid concentrations of 5-HIAA were 63.6 ng per milliliter ± 8.23 S.E.M. and 117 ng per milliliter ± 11.6 S.E.M. for the epilepsy and control groups respectively. HVA averaged 89.1 ng per milliliter ± 15.2 S.E.M. in epilepsy and 172 ng per milliliter ± 19.2 S.E.M. in the control group. These findings indicate a significant difference between epilepsy and control groups. Probenecid concentrations were similar in each group. The reduced cerebrospinal fluid amine metabolite concentrations in children with epilepsy were not related to age, anticonvulsant medication, cerebrospinal fluid folate or protein concentration, or cerebrospinal fluid cell count. Our findings suggest a relationship between brain amines and epilepsy.