1. Urinary d-glucaric acid excretion and plasma γ-glutamyl transpeptidase activity were measured in twenty-five out-patient and eighteen in-patient epileptic children receiving anticonvulsant therapy. Control specimens were obtained from twenty-three children receiving no medication.
2. d-Glucaric acid excretion greater than the control range was present in 88% of in-patients and 52% of out-patients. However, γ-glutamyl transpeptidase activity above the control range was found in 78% of in-patients and only 32% of out-patients.
3. In these forty-three epileptic subjects, there was a significant correlation between d-glucaric acid excretion and plasma γ-glutamyl transpeptidase activity.