Experiments were performed on 53 rats. The nociceptive discharges of spinal dorsal horn neurons were extracellularly recorded by glass microelectrodes and tested for the effects of angiotensin II (A II) on the nociceptive discharges of spinal dorsal horn neurons and AII on the inhibitory effects of electroacupuncture (EA). The results showed as follows: (a) The nociceptive discharges of spinal dorsal horn neurons might be inhibited (25/35) or facilitated (10) with A II (50-500 ng/20 ul) applied to the surface of dorsal spinal cord (L2-3); (b) The facilitory effects (5/5) were observed with A II (2 ug/20 ul) applied to the surface of dorsal spinal cord; (c) The inhibitory effects of EA (20 Hz, 2-4 V, 5 min) could be increased with A II (250 mg/20 ul, 8/9). Therefore, A II may modulate the nociceptive response of spinal dorsal horn neurons and influence the effects of EA, and different effects can be produced when the different dosage of A II is applied to the surface of dorsal horn.