To evaluate the antidiabetic activity of aqueous extract, of the whole plant of Cressa cretica L. Diabetes was induced by intravenous injection of Streptozotocin at dose of 60 mg/kg. Aqueous extract of the Cressa cretica L. at a dose of 200 mg/kg 400 mg/kg body weight was administered to Streptozotocin induced diabetic rats. The biochemical parameters cholesterol, triglycerides, HDL & LDL were also assessed in the experimental animals. The aqueous extract (200 mg/kg & 400 mg/kg) exhibited significant antihyperglycemic activity and it also decreased the biochemical parameters like cholesterol, triglycerides & LDL levels in treated groups as compared to these parameters in diabetic control. However HDL level was increased in treated animals as compared to the diabetic control group. The aqueous extract lowered the blood glucose level is almost near to the effect of the standard drug. This study supports the traditional claim that the aqueous extract of this plant could be added in traditional preparations for the treatment of various diabetes associated complications.