The antidiabetic effect of Gastrodia elata blume was investigated in streptozotocin-induced diabetic rats. Sprague-Dawley 30 rats, were divided into five groups, normal group(n=6), group Ⅰ was diabetic groups(n=6), group Ⅱ was diabetic induced and oral administration of Gastrodia elata blume extract 0.1 g/kg body weight(n=6) and group Ⅲ was diabetic induced and oral administration of Gastrodia elata blume extract 0.3 g/kg(n=6) and group Ⅳ was 0.5 g/kg(n=6) body weight for 28 days on Diabetic rats. Analysis the body weight, level of serum glucose, serum insulin, total cholesterol (TC), triglycerides (TG), aspartate transminase (AST), and alanine transaminase (ALT). Oral administrations of the Gastrodia elata blume extract significantly decreased weight, serum glucose, TC, TG, AST, and ALT levels, while increased in normal group. (p<0.05). TC and TG was significantly decreased in group Ⅲ and group Ⅳ. and AST, LT was no significantly in any groups. It is concluded that the Gastrodia elata blume must be considered as excellent candidate for future studies on diabetes mellitus.