Hyeonggaeyeongyo-tang (HYT; Jingjielianqiao-tang), is known to be effective in lowering wind-heat blended as a pathogen of kidney. HYT has been traditionally used for the treatment of a syndrome in kidney meridian, due to invasion of pathogenic wind and heat. Nowadays, this prescription is used to treat diseases marked by excessive wind and heat in the kidney meridian, such as acute otitis media, empyema, hypertrophic rhinitis, nasal bleeding, nasal obstruction, acne and tonsillitis. The present study was conducted to evaluate the effect of HYT on the regulatory mechanism of cytokines and nitric oxide (NO) for the immunological activities in Raw 264.7 cells. After the treatment of HYT water extract, cell viability was measured by MTT assay, NO production was monitored by measuring the nitrite content in culture medium. Cyclooxygenase-2 (COX-2_ and inducible nitric oxide synthase (iNOS) were determined by immunoblot analysis, and levels of cytokine were analyzed by sandwich immunoassays. The production of No was significantly inhibited by pre-treatment (1h) with HYT(0.1-0.3 mg/ml) on LPS-activated Raw264.7 cells. The expression of iNOS and COX-2 protein were up-regulated by LPS, but the increased levels of iNOS and COX-2 were inhibited by pre-treatment of HYT (0.3-1.0 mg/ml), respectively. And the level of interleukin-6 (IL-6), cytokine released from macrophage, was reduced by HYT pre-treatment (0.3-1.0 mg/ml). Thus, the present data suggest that HYT may play an important role in adjunctive therapy in Gram-negative bacterial infections.