Aim To investigate the effects of 1-o-acetylbritannilactone (ABL) isolated from Inula Britannica-F on activation of nuclear factor-κB (NF-κB) and cyclo-oxygenase-2 (COX-2) and intercellular adhesion molecule-1(ICAM-1) expression in human vascular endothelial cells (ECV304) treated with lipopolysaccharide (LPS). Methods ICAM-1 and nuclear P65 in protein extracts from ECV304 cells were detected by Western blotting. COX-2 mRNA was assayed by reverse transcription-polymerase chain reaction(RT-PCR). Results After ECV304 cells were incubated with 12.5, 25, 50 μmol/L ABL for 1 h, COX-2 mRNA level in ECV304 cells treated with LPS was reduced by 35.85%, 42.46% and 53.46%, respectively. Expression of ICAM-1 was decreased by 9.77%, 40.87% and 46.83%, respectively, compared with control group. ABL could antagonize the nuclear translocation of P65, and the increase in nuclear P65 induced by LPS no longer occurred following treatment with ABL. Conclusions ABL inhibits COX-2 and ICAM-1 expression in vascular endothelial cells by inhibiting NF-κB activation.