Capparis sepiaria L, a profusely branched hedge plant, is used in Indian traditional medicine. Capparis sepiaria leaves were extracted with ethanol and concentrated to dryness. The LD 50 value was determined as 894.43 mg/kg body weight by acute toxicity study. The ethanol extract was investigated for possible hypoglycemic effect produced by single oral administration at various dose levels 100, 200 and 300 mg/kg in the streptozotocin induced diabetic rats and compared against normal saline control and the standard glibenclamide. A maximum fall of plasma glucose level 9.40%; 13.57%; 15.25% and 18.80% was observed after 12 h of treatment when administered with ethanol extract of Capparis sepiaria at 100, 200 and 300 mg/kg, and glibenclamide 10 mg/kg dose, respectively. The findings from the study suggest that the Capparis sepiaria leaves may be prescribed as an adjunct to traditional formulation and drug treatment for controlling diabetes mellitus.