With the aim of identifying natural products, which possess hair-growing activity, we examined more than 1000 plant extracts with respect to their growth-promoting effects on hair epithelial cells. We discovered intensive growth-promoting activity, about 140% relative to controls, in barley extract. Our strategy for identifying active compounds in barley extract involved subjecting it to column chromatography using HP-20 resin columns, an LH-20 resin column, and preparative high-performance liquid chromatography (HPLC) using an ODS column. The 60% (v/v) aqueous methanol eluted fraction from the HP-20 column and the 75% (v/v) aqueous methanol eluted fraction from the subsequent LH-20 column showed high hair-growing activity in vivo. We isolated two major substances from the LH-20 active fraction using preparative HPLC. By means of mass spectrometry, 1H-NMR, and 13C-NMR analyses, one substance was revealed to be procyanidin B-3 and the other substance was identified as (+)-catechin. Purified procyanidin B-3 showed high hair-growing activity in the form of in vitro hair epithelial cell growth-promoting activity and in vivo anagen-inducing activity; however (+)-catechin showed no hair-growing activity. For the purpose of examining the hair-growing mechanisms of procyanidin B-3, we examined its relationship to the TGF-beta signal pathway, which is known to be a regulator of catagen induction. Addition of TGF-beta1 to hair epithelial cell cultures dose-dependently decreased the cell growth, and addition of procyanidin B-3 to the culture neutralized the growth-inhibiting effect of TGF-beta1. From these results, it is concluded that procyanidin B-3 can directly promote hair epithelial cell growth in vitro, has the potential to counteract the growth-inhibiting effect caused by TGF-beta1 in vitro, and has potential to stimulate anagen induction in vivo.