In this study, the auther has attempt to study electrophysiologically the aspect of pallidofugal fibers which are intermediated by the pallidum to the fibers arising from the motor area as the conduction system of epileptic discharge. Action potentials of motor cortex, basal ganglia, nuclei of the midbrain and spinal cord were recorded during major convulsive or subclinical seizures which are elicited by local administration of metrazol to the motor cortex or the thalamus of dogs. For subcortical recordings, a pair of bipor needle electrodes made of steel wire, mapproximately 200 μ in diameter on tungsten microelectrodes approximately 20 μ in diameter at the tip were used. Both steel and tungsten electrodes insulated by baking enamel except the tip. Spike discharges (duration of each spike is 20-60 msec. amplitude 50-100 μV recorded by abovementioned electrodes) are accounted for the epileptic discharges in this study. The results were as follows: 1) There are two different pathways transmitting the discharges from the motor area to the pallidum, one is direct connection between the motor cortex to the pallidum and the other has some relays the nuclei, thalamus and caudate nucleus, between them. These different pathways are connected separately to two different pallidofugal fiber group at the pallidum. 2) The pallidofugal fiber group, which is connected to the former pathways at the pallidum, are relayed at the contralateral substantia nigra and then terminated to anterior horn cells of the spinal cord. There is a fiber crossing to the other side at the midbrain between the pallidum and substantia nigra. 3) The pallidofugal fiber group connected to the latter at the pallidum does not show crossing to the other side on its course to the homolateral substantia nigra. But the downward fibers from the substantia nigra show a crossing to the other side at the pons and terminate in the contralateral anterior horn cells.