Hyungbangjihwangtang (HJT), a prescription of Sasang Constitutional Medicine, has been commonly used to treat diarrhea and edema of Soyangin in Korea. This study investigated the effect of HJT on lipopolysaccharide (LPS)-induced inflammatory cytokine production using peripheral blood mononuclear cells from the Soyangin. The inhibitory effect of HJT on LPS-induced inflammatory cytokine production was investigated using the enzyme-linked immunosorbent assay. Reverse transcriptase-polymerase chain reaction was used to investigate the interleukin (IL)-1beta mRNA expression. The expression level of nuclear factor (NF)-kappaB was examined by Western blot. HJT significantly inhibited the IL-1beta, IL-4, and tumor necrosis factor (TNF)-alpha production. The maximal inhibition rate of IL-1beta, IL-4, IL-6, IL-8, and TNF-alpha production by HJT was 240.0 +/- 48.8%, 78.4 +/- 24.7%, 27.6 +/- 10.6%, 20.7 +/- 59.8%, and 113.0 +/- 5.2%, respectively. HJT decreased the IL-1beta mRNA expression. HJT also inhibited the activation of NF-kappaB. These results suggest a potential role of HJT as a source of anti-inflammatory agent for inflammatory diseases.