To explore the pharmacological effect of 3,4-dihydroxyacetophenone (DHAP) on the apoptosis of RAW264.7 macrophage cells and the mechanism, RAW264.7 macrophage cells were treated with 100 or 500 mg/L lipopolysaccharide (LPS), with or without 10(-5) mol/L DHAP for 24 h. Trypan blue dye exclusion assay was used to assess cell viability. Cell apoptosis was morphological studied and flow cytometric assay was used. Tumor necrosis factor-alpha (TNF-alpha) level was measured by ELISA methods. IkappaB protein was determined by Western blotting. Our results showed that in 100 mg/L LPS-stimulated macrophages, DHAP enhanced the cell apoptosis while in 500 mg/L LPS-stimulated macrophages, DHAP significantly inhibited the cell apoptosis. In both groups, DHAP increased the level of IkappaB but decreased the level of TNF-alpha. It is concluded that DHAP has dual effect on the apoptosis of RAW 264.7 cells treated with different concentrations of LPS. This effect may be due to the inhibition of activation of NF-kappaB and autocrine production of TNFalpha. Our study suggests that DHAP may have anti-inflammatory effect on LPS-activated macrophages.