Diabetes mellitus is characterized by elevated blood glucose levels. The present study was to evaluate the antidiabetic potential of Hibiscus syriacus on alloxan induced diabetic rats. Animals are divided into five groups. For group I was administered with distilled water (10 ml/kg/p.o), group II with alloxan (120mg/kg/i.p), group III administered with alloxan and metformin (150mg/kg/p.o), group IV was received alloxan and ethanolic extract (200 mg/kg/p.o), group V received alloxan and ethanolic extract (400mg/kg/p.o). Administration of test and standard drug for the period of 28 days, on 28th day biochemical parameters were estimated. Results shows the decreased blood glucose level. Antidiabetic potential was high in group V compared to group IV. Hence It concluded that high dose of ethanolic extract shows the more antidiabetic potential compared to low dose.