To examine the effect of 3,4-oxo-isopropylidene-shikimic acid (ISA) on human polymorphonuclear leukocyte (PMN) adhesion to human umbilical vein endothelial cells (HUVEC) and explore its mechanism.Adhesion of PMN to HUVEC was measured by rose bengal staining assay. Cell-ELISA and RT-PCR methods were used to examine the expression of adhesion molecules ICAM-1. Cell viability was detected with MTT assay.ISA (1-100 micromol/L) effectively reduced PMN adhesion to TNF-alpha-induced HUVEC with the inhibitory rate from 17.2 % to 53.5 %, and exerted no effect on PMN adhesion to normal HUVEC. Adhesion molecule ICAM-1 surface protein and mRNA expression induced by TNF-alpha (400 kU/L) were significantly inhibited by ISA. In addition, the cell viability of HUVEC was unchanged 48 h after treatment with ISA.ISA inhibited TNF-alpha-stimulated PMN-HUVEC adhesion and expression of ICAM-1.