Background: Diabetes mellitus is a long-term metabolic illness that occurs due to a malfunction in the production or action of insulin. Prolonged hyperglycemia may lead to dysfunction and failure of several organs, such as the diabetic nephropathy, retinopathy and neuropathy. The incidence of diabetes and the number of patients has consistently risen over the last several decades. Juglans regia, a member of the Juglandaceae family, has been used by practitioners of folklore to treat number of illnesses. Aim: To Evaluate the antioxidant and anti-bacterial effects of a root extract from Juglans regia in in vitro studies and anti-diabetic effect Streptozotocin (STZ) induced Wistar albino rats. Methods: Qualitative phytochemical analysis, antioxidant assay were done using DPPH, antibacterial assay have been performed by using agar well diffusion method and anti-diabetic effect tested by inducing rats with STZ followed by administering methanolic root extract of Juglans regia alone and with adjuvants metformin and glipalamide. Result: The root extract of Juglans regia can decrease free radicals, possess antibacterial property in agar well diffusion method and in in-vivo studies group 2 (diabetic control) showed elevated FBS and HbA1C from day 3 to day 28 while group 3, 4, 5, 6, 7 and 8 showed significant reduction in FBS and HbA1C levels at the end of study. Safety profiles such as CBC, RFT and LFT did not show any significant difference between the groups from baseline to end of the study. Thus, methanolic root extract of Juglans regia was safe and efficacious against STZ induced rats. Conclusion: Juglans regia can reduce hyperglycemia in STZ induced diabetic rats alone and can be used as an adjuvant to Metformin and Glibenclamide. Also, it possesses anti-oxidant and anti-bacterial activity in in vitro studies.