Catecholamine and its metabolites level in cerebrospinal fluid (CSF), serum and urine of the 62 patients with epilepsy (38 males and 24 females, 12 cases of Lennox's syndrome, 48 cases of centrencephalic epilepsy, one case of focal cortical epilepsy and one case of temporal lobe epilepsy) were determined by gas chromatographic method (using an Electron Capture Detector) and fluorometric method. Studies on the epilepsy was performed with a special reference to catecholamine metabolism. As the results, 1) 3, 4-dihydroxyphenylalanine (DOPA) and dopamine in CSF of the epileptics were significantly lower than in the control group. 2) Homovanillic acid (HVA: end-product of dopamine) in CSF of the epileptics was also significantly lower than in the control group. 3) In epileptics tyramine, octopamine and synephrine were detected in CSF. 4) It is speculated in epileptics that the suppression of the pathway from tyrosine to dopamine may act to enhance the side pathway from tyrosine to tyramine followed by octopamine, synephrine and epinephrine. 5) Serum DOPA levels of epileptics being treated with anticonvulsants were abnormal in about half of the cases. 6) Serum MAO activity of epileptics was significantly lower than in the control group. 7) HVA in urine of epileptics tended to increase, but its level was changeable. Based on these clinical studies of epileptics, a penicillin focus was made on the cortex of cats. And effects of the catecholamines to penicillin focus were electroencephalographically examined. 8) Penicillin spikes were strongly inhibited by topical application of dopamine. 9) When octopamine was injected into cisterna magna after the appearance of penicillin spikes, spike frequency increased and abnormal spike discharges were observed.