Dilazep dihydrochloride (dilazep) is used to treat ischemic dysfunction, although the mechanisms underlying the anti-inflammatory effects of the drug have not yet been elucidated. The present study evaluated the anti-inflammatory effect of dilazep. Dilazep suppressed the production of nitric oxide (NO) and the expression of TNF-α mRNA by lipopolysaccharide (LPS) in RAW 264 cells. However, 1400W, an inducible NO synthase inhibitor, suppressed the production of NO but did not suppress the expression of TNF-α mRNA following treatment with LPS. Caffeine, an adenosine antagonist, restored LPS-stimulated NO synthesis, which is suppressed by dilazep. Therefore, these observations may suggest that the suppression of NO synthesis after dilazep treatment in RAW 264 cells is caused by the inhibition of TNF-α expression via adenosine receptors.