The pathobiologic process of arterial stenosis following balloon angioplasty continues to be an enigmatic problem in clinical settings. This study investigates the ability of demethoxycurcumin, a curcuminoid isolated from Radix Curcumae, to attenuate balloon injury-induced neointima(NI) formation in the rat carotid artery. It was found that demethoxycurcumin induced inducible heme oxygenase(HO-1) expression and inhibited dose-dependently cellular proliferation in rat vascular smooth muscle cells. Perivascular application of demethoxycurcumin immediately following injury significantly reduced NI area and NI thickness 2 weeks post-injury. Interestingly, treatment with tin-protoporphyrin IX, a HO inhibitor, reversed the effects of demethoxycurcumin on NI formation. These results implicate demethoxycurcumin as a potent new therapeutic agent that is capable of reducing post-angioplasty arterial stenosis through induction of the HO-1 expression.