Effect of diazepam on the activity of the epileptic complex consisting of a number of foci created with strychnine applications to the brain cortex under conditions of intact brain and at different levels of it neuronal isolation was studied in acute and chronic experiments on cats. It was shown that in the preparations of cerveau isolé and cortex isolé a more rapid formation of the epileptic complex under the influence of the determinant focus, and marked generalizaiton of convulsant activity could be observed. Diazepam induced a decrease in the amplitude and frequency of convulsive discharges. There was a break in the synchronization of their appearance first in the dependent foci and then in the determinant one. The diazepam effects were seen both in the intact brain and in the preparations of cerveau isolé and cortex isolé. These findings indicate that diazepam may exert an indirect action on the brain cortex that does not exclude the participation of other brain structures in the realization of the diazepam effect under conditions of intact brain.