To evaluate the in vitro α- glucosidase inhibitory activities of ethanolic extract from aerial part of Oldenlandia corymbosa. Postprandial hyperglycemia which was focused in the therapy for diabetes was the prime characteristic of diabetes mellitus. Pancreatic α- glucosidase inhibitors techniques lower the levels of postprandial blood glucose levels by controlling carbohydrate metabolism and they are the most effective. The therapeutic methodologies includes diminishing hyperglycemia goes for inhibiting the enzyme α- glucosidase. Herbal remedies are well known for their establised ability and acceptability together with lower expenditure and lesser side effects for which they were considered more aporopriate for our study. The ethanolic extract obtained was subjected to in vitro alpha glycosidase inhibitory assay for which starch azure was used as the substrate and porcine pancreatic amylase as the enzyme . Enzyme solution was premixed with the extract at various concentrations (20, 40, 60, 80 and 100 mg/ml).Colorimetric reagents and Substrate solutions were added to the reaction. Spectrophotometric method was used to measure the release of glucose. The positive control used was acarbose. The extract (20 to 100 mg/ ml) was found to inhibit α- glucosidase activities. The extract has shown higher reduction of α-glucosidase. Inhibition at various concentrations were significantly different (p<0.05).The results shows 90% reduction in α- glucosidase activity. This finding tells the utilization of ethanolic extract of aerial plant of Oldenlandia corymbosa is effective in inhibiting α-glucosidase thereby proving to be potential anti-diabeteic agent.