Cordyceps possesses numerous health-promoting ingredients including hypoglycemic agents. The mechanism for the reduction of circulatory sugar content, however, is still not fully understand. In this study, 4-beta acetoxyscirpendiol (ASD) was purified from the methanolic extracts from fruiting bodies of Paecilomyces tenuipes. Na+/Glucose transporter-1 (SGLT-1) was expressed in the Xenopus oocytes. The effect of ASD on the oocyte expressed SGLT-1 was analyzed utilizing the voltage clamp and 2-deoxy-D-glucose (2-DOG) uptake studies. ASD was shown to significantly inhibit SGLT-1 activity compared to the non-treated control in a dose- dependent manner. In the presense of its two derivatives (diacetoxyscirpenol or 15-acetoxyscirpendiol), SGLT-1 activity was greatly inhibited similarly as ASD. Between ASD derivatives, 15-acetoxyscirepenol showed inhibition equivalent to that of ASD while diacetoxyscirpenol did less degree of inhibition. Insummary , these results strongly indicate that ASD in P. tenuipes may serve as a functional substance in lowering blood sugar in the circulatory system. ASD and its derivatives can be utilized as inhibitors of SGLT-1.