Local anesthetics possess a wide range of anti-inflammatory properties through their effects on neutrophils. However, limited information is available on the effects of ropivacaine (a new local anesthetic) on neutrophil function. The aim of this study was to investigate anti-inflammatory properties of ropivacaine with regard to its effects on the expression and function of CD11b in human neutrophils. CD11b expression was examined by flow cytometry and its function was determined by measuring adhesion of neutrophils to human umbilical vein endothelial cells (HUVECs). Ropivacaine inhibited CD11b expression in formyl-methionyl-leucyl-phenylalanine (fMLP)-activated neutrophils in a concentration-dependent manner, but not in a time-dependent manner. The inhibitory potency of ropivacaine was similar to that of bupivacaine and levobupivacaine, but was more potent than that of lidocaine. The up-regulation of CD11b induced by platelet-activating factor (PAF) priming was also inhibited by ropivacaine. fMLP increased adhesion of neutrophils to HUVECs, which was inhibited by ropivacaine. In addition, ropivacaine more potently inhibited the fMLP-induced CD11b expression in the presence of ethylene glycol-bis(2-aminoethylether)-N,N,N ,N -tetraacetic acid (EGTA), a chelator of extracellular Ca(2+). However, ropivacaine showed no effect on the fMLP-induced CD11b expression in the presence of butan-1-ol, a blocker of phospholipase D (PLD) pathway, which completely inhibited the fMLP-induced CD11b expression in neutrophils. Our results suggest that ropivacaine exerts anti-inflammatory activity, and this appears to be mediated through inhibiting the expression and function of adhesion molecule CD11b in neutrophils.