Abstract--Many plant drugs are studied for effecting in the treatment of Diabetes mellitus. In the present study ethanolic extract of herb of Catharanthus pusillus was evaluated for hypoglycemic effect in Streptozotocin induced diabetic rats using both 18 hour fasted rat model and oral glucose tolerance test. A comparison was made between the actions of ethanolic extract Catharanthus Pusillus and known anti diabetic drug Glibenclamide (5 mg/kg, p.o). The ethanolic extract of Catharanthus Pusillus was administered at different doses to normal and diabetic rats. The ethanolic extract at 500 mg/kg body weight dose level exhibited significant hypoglycemic activity (P < 0.01 and P < 0.001). Phytochemical screening of aqueous, methanolic, ethanolic and chloroform extract revealed the presence of alkaloids, saponins and carbohydrates. It is concluded that ethanolic extract of herb of Catharanthus Pusillus posses anti diabetic activity.