Vigna radiata is an important medicinal plant that belongs to family Fabaceae, which is widely used in the traditional medicine all over the word. Behind its nutritional acceptance, the grain of this plant is cocked traditionally and consumed for the purpose of lowering the blood glucose level in diabetic patients especially in rural areas. This study was designed to scientifically validate its antidiabetic activity in diabetic mice. Mice obtained from Ethiopia public health institute were allowed to adapt the experimental room for 3 days before the actual experiment. They consumed the standard food (pellet) throughout the experiment. After dissolving streptozotocin with 0.9% normal saline, the fresh solution was injected to all mice through intraperitoneal route at a dose of 35 mg/kg. The diabetic mice were divided in to four groups. The first group was treated with glibenclamide (5mg/kg), the second group was treated with normal saline (10 ml/kg) and the last two groups were treated with aqueous extract of v.radiata at 200 and 300 mg/kg. Finally, blood glucose levels were measured 1hr, 2hr, 3hr and 4hr after administration of each treatment. The aqueous crude extract at 200 and 300 mg/kg decreased the blood glucose level as compared to the control group (p<0.05). The antidiabetic activity of aqueous extract of v.radiata at 200mg/kg was lower than that of the aqueous extract at 300mg/kg. In conclusion, the aqueous crude extract of v.radiata possesses a significant antidiabetic activity.