Functional brain imaging studies of the specificity of acupoint stimulation have revealed that needling at particular acupoints can induce activation of corresponding brain areas, examined in physiological and pathological states. The present study examined Waiguan (SJ 5) as the acupoint of interest. We tested five conditions: a true needling at true acupoint group, a sham needling at true acupoint group, a true needling at sham acupoint group, a sham needling at sham acupoint group, and a healthy control group. We examined changes in glucose metabolism in different functional cortical regions to determine the specific brain activation elicited by acupuncture at Waiguan. The results revealed that true and sham acupuncture at the same acupoint activated different brain regions. In addition, applying acupuncture at a genuine acupoint and a neighboring sham acupoint activated different brain regions. These findings suggest that acupuncture at Waiguan causes activation in some brain regions.