Average evoked responses (AERs) were recorded simultaneously from 3 hypothalamic nuclei of freely behaving rats. Permanent semi-microelectrodes were implanted 6–8 days before experiments were begun. The amygdaloid AER to 32 successive stimuli consisted of large amplitude potentials made up of 3 components (P1, N1 and P2) with short latencies. The neuronal recovery function (NRF) was short. However, the acoustic AER to 32 successive acoustic stimuli in anterior hypothalamus (AH), ventromedial hypothalamus (VMH), and arcuate nucleus (AN) consisted of large amplitude potentials of long duration made up of 5 components (P1 N1, P2, N2 and P3) with long latencies. The NRF was long. Intraperitoneal administration of L-dopa heightened the amplitude of the acoustic AER and shortened the NRF in VMH and AN. Reserpine administration 2 h after L-dopa maintained these phenomena in VMH and AN without alteration of the AER and NRF in AH. When reserpine was administered first, enhancement of the acoustic AER and shortening of the NRF was again obtained only in VMH and AN. L-dopa injection after reserpine treatment maintained these phenomena. Low doses of pentobarbital after L-dopa and reserpine and vice versa caused a marked increase in the acoustic AER and a shortening of the NRF in all recording sites. The amygdala AER and NRF, however, were not altered by any treatment or in any recording site