and NorthEastern parts of India. The leaves have been traditionally used in the treatment of diabetes and urinary disorders. The leaves were also known to possess potent antioxidant activity. Objective: Aim of the study was to investigate the in-vitro and in-vivo anti-diabetic activity of different extracts of leaves of Actinodaphane hookeri. Materials and Methods: The leaves of Actinodaphane hookeri were extracted successively with petroleum ether (AHP), chloroform (AHC), methanol (AHM) and water (AHA). Also, the leaves were extracted separately with alcohol (AHT). Extracts were subjected to phytochemical investigation and evaluated for its in-vitro anti-diabetic activity by α-glucosidase inhibitory activity, and in-vivo anti-diabetic activity was carried out in STZ-induced diabetic rats at two dose levels viz. 300 and 500 mg/kg doses for 21 days. Results: Phytochemical screening showed the presence of sterols, triterpenes, alkaloids, flavonoids, tannins, lactones and mucilages. The in-vitro αglucosidase inhibitory activity was highest in AHC with an IC 50 value of 309.04 ± 0.02 μg/ml and lowest in AHA with an IC 50 value of 812.86 ± 0.03 μg/ml. Significant decrease in blood sugar, gain in body weight, decrease in TCH, TG, LDL and VLDL and increase in HDL levels were observed. Potent activity was observed in AHC followed by AHP, AHT, AHM and AHA. Histopathological investigation showed pancreatic β-cell protection. Conclusion: The findings suggest that Actinodaphne hookeri Meissn. leaves have potent anti-diabetic activity. INTRODUCTION: Diabetes Mellitus (DM) is known to Indians from Vedic period onwards by the name Asrava (Prameha, derived from the Sanskrit words mih sechane meaning 'watering' that means dilution of everything in the body.