This study explored the effects over time of lactic acid (LA) on I Bα phosphorylation and nuclear factor-kappa B (NF- B) p65 protein expression, and on tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) mRNA levels in rat intestinal mucosa microvascular endothelial cells (RIMMVECs) stimulated by lipopolysaccharide (LPS). I B , phosphorylated I B (p-I B ) and p65 protein levels were monitored by Western blot analysis, and TNF- and IL-6 mRNA levels were analyzed using real-time PCR. LA treatment reduced TNF- and IL-6 mRNA levels in LPS-stimulated RIMMVECs, with the greatest effect being after 3 h. The highest inhibitory effect of LA on I B phosphorylation to prevent activation of NFB was after 6 h. These results suggest that LA reduces TNF- and IL-6 mRNA levels through decreasing I B phosphorylation and blocking the dissociation of IKK complex, which prevents activation of NF- B.