In order to validate the use of Radix Curcumae Aromaticae as an anti-inflammatory drug in the traditional Korean medicine, I have investigated the effect of water-soluble extract of Radix Curcumae Aromaticae (ECA) on the expression of inducible heme oxygenase-1 (HO-1), which ha.s anti-inflammatory and cytoprotective effects stimulates, in human umbilical vein endothelial cells (HUVECs) stimulated with a high dose of pro-inflammatory tumor necrosis factor-alpha (TNF-α). The extract protected dose-dependently HUVECs against TNF-α-induced apoptosis, as measured qualitatively by a nuclear staining method using the fluoresoence DAPI and quantitatively by a flow cytometry using fluoresce-enhanced Annexin V antibody, and significantly Increased HO-1 expression, as determined by Western blotting analysis using anti-HO-1 antibody. Biockage of HO-1 activity by a pharmacological inhibitor reversed cytoprotection afforded by the extract, and treatment with carbon monoxide, one of HO-1 metabolites, resulted in cytoprotection comparable to the extract. These results suggest that ECA may have therapeutic potential in the control of endothelial disorders caused by inflammatory cytokines.