Abstract: AIM To investigate the inhibitory effects of hydrocortisone on human polymorphonuclear leukocyte (PMN) adhesion to human synovial cell (HSC), and to explore its mechanism. METHODS MTT colorimetry was used to determine the adhesion effect of PMN to HSC. Cell-ELISA and RT-PCR methods were used to determine the expression of adhesion molecular ICAM-1 and VCAM-1. EMSA method was also used to observe the activity of nucleus transcription factor-κB (NF-κB). RESULTS Hydrocortisone inhibited TNF-α (50 U·mL^-1 for 12 hours) and IL-1β (50 U·mL^-1 for 12 hours) induced adhesion of PMN to HSC (IC50 2.05×10^-6 mol·L^-1 and 2.13×10^-7 mol·L^-1, respectively) in a concentration dependent manner. Adhesion molecular VCAM-1 and ICAM-1 protein and mRNA (rather than ICAM-1) expression in HSC induced by TNF-α (50 U·mL^-1) were inhibited significantly by hydrocortisone at 1×10^-6 -10^-5mol·L^-1. The activity of NF-κB was also extensively inhibited by hydrocortisone at 1×10 ^-6 -10^-5mol·L^-1. CONCLUSION Hydrocortisone inhibited TNF-α-stimulated PMN HSC adhesion, and expression of VCAM-1 by suppressing the activity of NF-κB.