As inhibitors of carbohydrate-digesting enzymes can prevent hyperglycemia that is known to cause many macrovascular complications, they may prove a useful adjunct to hypocaloric diets in patients with type 2 diabetes and obesity. Inhibitory activities of two hundred and fifteen kinds of medicinal herb extracts against $alpha$-glucosidase (EC 3.2.1.20) and $alpha$-amylase (EC 3.2.1.1) have been investigated in vitro. Adenophora triphylla, Aneilema keisak, and Morus bombysis significantly suppressed rat intestinal $alpha$-glucosidase activity iu vitro. Porcine pancreatic amylase was efficiently inhibited by methanol extracts of Epimedium koreanum, Campsis grandiflora and Salvia plebeia. Methanol extract of Epimedium koreanum among the medicinal herbs tested showed the strongest inhibitory activity against porcine pancreatic $alpha$-amylase with 0.1 mg/ML of $IC_{50}$/. The herb extract also improved glucose tolerance in ICR mice when loaded with 0.9 g soluble starch per kg body weight. Taken together, Epimedium koreanum merits further evaluation as a therapeutic measure.