Abstract: α-Glucosidase in vitro inhibitory activity and hypoglycemic effect by oral administration in rats of Phaleria macrocarpa fruit extracts have been conducted. The hypoglycemic activity of α-glucosidase inhibitor is resulted from a competitive, reversible inhibition of pancreatic α-amylase and membrane bound intestinal hydrolase enzyme such as isomaltase, maltase and sucrase. In diabetic patients, inhibition of these enzymes results delayed glucose absorption and a lowering a postprandial hyperglycemia. The purpose of this study is to investigate the hypoglycemic activity of fruit extracts of Phaleria macrocarpa (Scheff) Boerl. as an α-glucosidase inhibitors by in vitro and in vivo experiments. α-Glucosidase inhibitory activity evaluation showed that the n-butanol of young and ripe fruit extracts have the highest activity, followed by ethyl-acetate and methanol extracts. By oral administration to rats, the hypoglycemic activity has been showed that the boiled water extract of ripe fruit with dose of 6.20x10-3 and 1.24x10-3 mg g-1 , n-butanol extract of ripe fruit with dose of 1.81x10-3 and 3.62x10-3 mg g-1, respectively, decreased the blood glucose concentration of rats after treated with 80% w/v sugar solution, being comparable to those of acarbose 1.00x10-3 mg g-1 rat as the positive control.