Background: Noninsulin-dependent diabetes mellitus (NIDDM) is a common disease of the endocrine system caused by the decreased secretion of insulin by the pancreatic Langerhans beta cell or by the lowering of insulin resistance due to excessive absorption of glucose. The Siddha system of medicine is a traditional medical system that uses a scientific and holistic approach to provide preventive, promotive, curative, rejuvenative and rehabilitative health care. According to Siddha literature, diabetes is known as Innippu Neer, Madhumegam and Neerizhivu. The various reasons for the cause of this disease are attributed to foodhabits and lifestyle changes and also due to hereditary causes. One of the therapeutic approaches is to decrease the postprandial hyperglycemia by retarding the absorption of glucose through the inhibition of carbohydrate-hydrolyzing enzymes, such as a-amylase and ?-glucosidase. ?-Glucosidase are enzyme that catalyze the absorption of digested glucose from dietary polysaccharides in the small intestine. Aim: The aim of the present study is to evaluate the anti-diabetic potential of the siddha formulation of Sambirani Poo Kuligai(SPK) by alpha glucosidase enzyme inhibition assay. Method: The spectrophotometric assay method was used to find alpha glucosidase inhibitory activity. Results: SPK showed presence of alpha glucosidase inhibitory potential with the maximum inhibition of about 41.74 ± 3.578 % and the corresponding IC50 is 606.5 ± 49.51?g/ml. Conclusion: This in-vitro study revealed the presence of the alpha glucosidase activity in the siddha formulation Sambirani Poo Kuligai possesses antidiabetic activity