||Alcoholic and aqueous extract of tuberous roots of Decalepis hamiltonii (DH) were prepared and given individually orally at different doses to different groups of rats fasted for 18 h (both normal and streptozotocin (STZ) induced diabetic albino rats). The serum glucose levels were measured initially at 0 h (before treatment) and at 0.5, 1, 2, 3, 4, 6, 8, 12, 16, 20 and 24 h after the treatment. The alcoholic extract of tuberous roots of D. hamiltonii (AETRDH) at higher dose (200 mg/kg) produced maximal serum glucose lowering effect in both normal and STZ induced diabetic rats. The aqueous extract of tuberous roots of D. hamiltonii (AQETRDH) produced maximal percent reduction in serum glucose levels with higher dose (400 mg/kg). AETRDH and AQETRDH produced hypoglycemic and antidiabetic activities at 3 h in normal and STZ induced diabetic rats in a dose dependent manner. The effect produced by AETRDH was found better than that of standard gliclazide (2 mg/kg) an oral hypoglycemic agent. The AETRDH has exhibited higher and better hypoglycemic and antidiabetic activity for a prolonged period than that of the AQETRDH.