The effects of electro-acupuncture on the pain threshold and the amplitude of dEMG(di-gastric EMG) evoked by the noxious electric stimulation on teeth and gingiva in dogs were studied. Experiments were carried out with 10 dogs weighing 5-8kg. Each animal was anestheticed with Entobar given intraperitoneally in an initial dose of 30mg/kg. Maintenance dose of 5mg/kg/hr was given through a cannula, in the femoral vein, as required to keep up light anesthesia. Bipolar stimulating wire electrodes, 0.1mm in diameter, insulated except for tips, were inserted into the upper canine and palatal gingiva. Rectangular aluminium plate electrodes (15$ imes$5mm) were placed on acupuncture points, called Yin-Hsiang, located at both sides of the upper jaw. Rectangular biphasic current pulses of 2Hz, with a $250{mu}sec$ duration, were delivered for 15 minutes. The dEMG activities were recorded from the anterior belly of the digastric muscle(one of the jaw opening muscles) using bipolar wire electrodes. The magnitude of the jaw opening reflex at different intensties of electro-acupuncture(1volt 4volt and 10volt) was estimated by averaging the 30 superimposed dEMGs recorded on an oscilloscope and audiomonitor. Data were analysed statistically with ANOV A and paired t-test. The obtained results were as follows: 1. Pain thresholds were increased 7.7 %, 15.4 %, 17.3 % in the teeth and 11.1 %, 19.0 %, 25.4 % in the gingiva as the intensities of electro-acupuncture increased incrementally. 2. Amplitudes of dEMG were decreaed 8.3%, 22.4%, 27.4% in the teeth and 9.8%, 36.5%, 42.2 % in the gingiva as the intensities of electro-acupuncture increased incrementally. 3. Inhibition of pain responses by the electroacupuncture was more effective in the gingiva than in the teeth.