The effect of electroacupuncture (EA) on minimum alveolar concentration (MAC) of isoflurane was evaluated in dogs. After determination of baseline MAC, EA was applied at each acupoints (LI-4, SP-6, ST-36 and TH-8) and nonacupoint for 30 min. MAC was determined again. EA at acupoints significantly lowered the MAC of isoflurane in dogs (17.5 +/- 3.1%, 21.3 +/- 8.0%, 21.2 +/- 7.5% and 15.4 +/- 3.1%, respectively). In control group and nonacupoint electrical stimulation group MAC were not decreased significantly. From these results, electroacupuncture at each acupoints used in the present study would have an advantage in isoflurane anesthesia with reducing its requirement.