To elucidate antidiabetic activity of Lycii Fructus. The extract of the Lycii Fructus was subjected to bioactivity-guided fractionation. The extract of the Lycii Fructus was partitioned suceesively with hexane, dichloromethane, ethylacetate and butanol. The butanol fraction, which is most abundant in the Lycii Fructus was subjected to silica gel column chromatography and resulted in seven fractions namely Fr. I - Fr. VII. Among tested several subfractions, Fr IV. Showed the highest antidiabetic activity in the streptozotocin-induced model rat.