Objectives : In this study, water extracts from Coix lachryma-jobi Linne var. mayuen Stapf. were investigated for their effects on insulin-like action and glucose uptake in 3T3-Ll cells. Methods : We examined the effects of insulin-like action on the differentiation of 3T3-Ll fibroblasts. The Coicis Semen was treated with hot water and the extract was freeze-dried. The hot water extract was chromatographed on nonionic polymer resin (Amberlite XAD-4, Sigma) with distilled water (Fr. 1), 20% (Fr. 2), 40% (Fr. 3), 60% (Fr. 4), 80% (Fr. 5), and 100% EtOH (Fr. 6), successively. Results : Total extract of Coicis Semen was fractionated into 0 to 100% MeOH with Amberlite XDA-4 column. Treatment of cells with $10{;}mu extrm{g}/ml$ of total extracts of Coicis Semen significantly increased the differentiation (p<0.05). At $1{;}mu extrm{g}/ml$ level of insulin, the differentiation was accelerated (p<0.01). The effect of extracts plus insulin on the differentiation was greater than that of insulin alone. In 3T3-Ll adipocytes, glucose uptake was higher by 2.7 times with 5 uM of total extract in low dosage of insulin (3 ng/ml) than without total extract. 5 and 50 uM of water and 40% MeOH fractions increased glucose uptake by 3.5 times in 3T3-Ll adipocytes (p<0.00l). Conclusions : Coicis Semen contains compounds which playa role of insulin-like action and insulin sensitizer.