Background and Objective: The effect of laser acupuncture on obesity in postmenopausal women remains unknown. The aim of this study was to investigate the effects of this form of treatment using an animal model. Materials and Methods: Seventy-seven female Sprague-Dawley rats were assigned into seven groups: normal control (Normal), sham-operation control (Sham), ovariectomized (OVX) control rats (OVX), OVX rats treated with estrogen (OVX + E), and three groups of ovariectomized rats treated with laser acupuncture (OVX + L). Bilateral ovaries were removed to decrease estrogen levels. After 2 wk, semiconductor laser irradiation was administered to bilateral Shenshu (BL 23) acupoints of rats in the three OVX + L groups at 12, 30, and 60 J/cm(2), respectively. Changes in body weight and pituitary estrogen receptor (ER) mRNA expression were analyzed. Morphological differences in the uterus and pituitary glands were also observed. Results: The OVX group exhibited marked weight gain and a significant decrease in pituitary ER alpha mRNA expression. Semiconductor laser irradiation at 30 J/cm(2) reduced body weight and increased ER alpha expression compared with the control, whereas irradiation at 12 or 60 J/cm(2) presented slightly weaker effects. Significant differences in pituitary ER beta mRNA were not observed due to lack of optical density data. Conclusions: The semiconductor laser irradiation of bilateral Shenshu (BL 23) acupoints can exert beneficial effects on OVX rats through reducing body weight and increasing pituitary ER alpha expression, and 30 J/cm(2) was the most effective dose among those used.