Alpha glucosidase is a potential target enzyme in the management of diabetes mellitus. Diabetes mellitus (DM) is a metabolic disorder caused by defect in insulin secretion, insulin action, or both. Insulin deficiency as such results to a chronic hyperglycemia with disturbances of carbohydrate, fat and protein metabolism. The current work studied the in vitro inhibitory potentials of stem bark extracts of Albizia lebbeck on yeast α-glucosidase activity using p-nitrophenyl-α-D-glucopyronaside (PNPG) as substrate. The Stem Bark of Albizia lebbeck was collected from the university premises of Usmanu Danfodiyo University Sokoto Nigeria. The stem bark was extracted with methanol and further with hexane and ethyl acetate fractions using separation funnel. Crude α-glucosidase was obtained from yeast (Saccharomyces cereviceae). The hexane and methanol extracts were tested for inhibitory potentials on α-glucosidase and the IC50 was calculated. The results indicated that at 10, 30 and 50mg/ml, the hexane extract caused 20.65, 36.52 and 61.96% reduction in the activity of α-glucosidase respectively. The methanol extract on the other hand inhibited the activity of the enzyme by 14.36, 24.30 and 31.29% respectively. The IC50 was calculated for the hexane and methanol extracts to be 1.68 and 2.92mg/ml respectively. The results of this study therefore concluded that hexane and methanol extracts of Albizia lebbeck stem bark possesses significant inhibitory effect on α-glucosidase in a dose dependant manner and may therefore have potentials as a source of lead for the development of anti-diabetic drugs.