Acetylsalicylic acid and sodium salicylate inhibit LPS-induced NF-kappa B/c-Rel nuclear translocation, and synthesis of tissue factor (TF) and tumor necrosis factor alfa (TNF-alpha) in human monocytes. We have investigated the effects of acetylsalicylic acid and sodium salicylate on the LPS-induced synthesis of the pro-coagulant protein tissue factor (TF) and the pro-inflammatory protein tumor necrosis factor-alpha (TNF-alpha), as well as the prostaglandin PGE2 in human monocytes. Both drugs dose-dependently inhibited LPS-induced TF and TNF-alpha synthesis at the mRNA and the protein level, and reduced PGE2 production. As evidenced by electro mobility shift assay (EMSA) and the use of a NF-kappa B prototypic probe, these drugs probably exert their inhibitory effects by interference with the nuclear translocation of NF-kappa B/c-Rel proteins. These data may expand the understanding of the anti-thrombotic and anti-inflammatory effects of these drugs when activation of monocytes occurs.