Inflammation is a frequent radiation-induced following therapeutic irradiation. Treatment of human umbilical endothelial cells (HUVEC) with ${gamma}$-irradiation (${gamma}$IR) induces the expression of adhesion proteins such as intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin. Since the upregulation of these proteins on endothelial cell surface has been known to be associated with inflammation, interfering with the expression of adhesion molecules is an important therapeutic target. In the present study, we demonstrate that bioflavonoid rutin inhibits ${gamma}$IR induced expression of ICAM-1, VCAM-1, and E-selectin on HUVEC in a dose- and time dependent manner. Rutin also inhibited ${gamma}$IR induced production of NO. These data suggest that rutin has therapeutic potential for the treatment of various inflammatory disorder associated with an increase of endothelial leukocyte adhesion molecules.