This study was performed to investigate that electro-acupuncture might relieve chronic back pain in horses. Twenty horses with chronic back pain were chosen from referring to College of Veterinary Medicine, University of Florida. They were assigned the patients referred to 2 treatment groups and 1 control group. The treatment group I was electrostimulated to 4 acupoints. The acupuncture points of Lumbosacral point, GV-6, BL26, and BL54 were used.; The treatment group II was taken the phenylbutazone orally. Control group was administered the normal saline per oral. Back pain score system was used to evaluate the degree of back pain. The treatment group r had significant lower back pain score from two times of electroacupuncture treatment. However, the treatment group II and control group did not change back, pain scores during experimental periods. Thus, Electroacupuncture treatment might be effective therapy for chronic back pain in horses.