This study was designed to examine the effects of fractions of ethanol extract of Benincasa hispida (wax gourd) on plasma glucose and lipid levels in streptozotocin (STZ) induced diabolic rats. sprague-Dawley rats were induced diabetes mellitus by STZ injection (45 mg/kg) into the tail vein and were divided into 5 groups: normal, STZ-control, three experimental diabetic groups. fractions of ethanol extract of Benincasa hispida were administered orally into the diabetic rats for 14 days. The food intake and body weight were monitored and plasma levels of glucose, cholesterol, HDL-cholesterol, triglyceride (TG) , free fatty acid (FFA) , and aminotransferase activity were analyzed. A significant lowering effects of plasma glucose levels were observed in the chloroform fraction and $H_2O$ fraction group compared to STZ-control group at 14 days. Administrations of each of the three fractions decreased plasma TG and FFA levels in diabetic rats. Activity of alanine aminotransferase (ALT) in $CHCl_3$ fraction and $H_2O$ fraction groups and aspartate aminotransferase (AST) in $H_2O$ fraction group significantly lower than STZ-control group. The results show that $CHCl_3$ fraction of Benincasa hispida could be effective to control the STZ-induced diabetic rats. (Korean J Nutrition 38(10): 801$sim$806,2005)