The objective of this study was to evaluate the antihyperglycemic activity of Blighia sapida arils (mature and immature) on Wistar rats. Forty-two (42) rats were divided into seven batches. They were made hyperglycemic by sugar water administration at concentration of 2500 mg/L. Rats in batches 1, 2 and 3 were administered 200, 400 and 800 mg/Kg of body weight of mature arils of Blighia sapida respectively, while those in batches 4, 5 and 6 received 200, 400 and 800 mg/kg of body weight of immature arils respectively. As for the control batch, it received distilled water. Immature arils of Blighia sapida lower blood sugar levels more than mature arils. The decrease of glycemia can be justified by the presence of hypoglycin A which is higher in immature arils than mature arils. The use of hypoglycin A as an antidiabetic agent should be considered. Further, studies are needed to evaluate the impact of blocking β-oxidation on insulin secretion. It would also be important to determine therapeutic doses, which should be low given the known toxic effects of hypoglycin A.