This paper investigates how BST204, a fermented ginseng extract, affects the expression and mechanism of cyclooxygenase-2 (COX-2). BST204 was prepared by incubating crude ginseng extract with ginsenoside-beta-glucosidase. Unexpectedly, BST204 had no effect on the level of COX-2 protein in unstimulated RAW 264.7 cells, and it suppressed the level of COX-2 protein and PGE(2) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. It did not show any suppressive effect, though, on the COX-2 mRNA level. To investigate the suppressive mechanism of COX-2 protein, the activating phosphorylation of p70 S6 kinase and 4E-BP1, which are important for translation, were measured. The phosphorylation of p70 S6 kinase, not 4E-BP1, was increased by LPS in a time-dependent manner, and was inhibited by BST204 in a dose-dependent manner. The expression of COX-2 protein, however, was partially suppressed by rapamycin, an upstream inhibitor of p70 S6 kinase. Therefore, this paper suggests that the suppression of COX-2 protein by BST204 was partially correlated with the inhibition of p70 S6 kinase activation.