This study was performed to investigate the effects of xylazine on the motility of abomasum and proximal colon in cattle. Bipolar electrodes were implanted in the subserosa of the abomasum and colon. Electromyogram of the motility was recorded by polygraph after intramuscular administration of xylazine at the doses of 0.1 and 0.2 mg/kg. The mtility of abomasum was completely inhibited at 5~11 minutes after xylazine administration. However, that of the abomasum was reappeared at 15 minutes and greatly increased to supranormal motility at 41~51 minutes, then recovered to normal activity at 70~123 minutes. Meanwhile, the motility of proximal colon was completely inhibited at 3~10 minutes and reappeared at 60~150 minutes after xylazine administration, then recovered gradually to normal pattern at 240 minutes. Our data indicate that xylazine (0.1~0.2 mg/kg) affect on the abomasal motility in a biphasic manner, initial inhibition and following activation, but on the colon motility in a monophasic inhibition.