Benjakul (BJK), a Thai traditional medicine preparation, has long been used for balanced health, controlled abnormal of element in the body, carminative, and relief of flatulence. It is composed of five plants: Piper interruptum Opiz., Piper longum L., Piper sarmentosum Roxb., Plumbago indica L., and Zingiber officinale Roscoe. The ethanolic extracts of BJK, its five individual plants, and pure constituents of BJK were investigated for their anti-allergic activity using immunoglobulin E (IgE)-sensitized β-hexosaminidase in the rat basophilic leukemia-2H3 (RBL-2H3) cells and anti-inflammatory activity using lipopolysaccharide (LPS)-induced nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α) in the murine macrophage (RAW 264.7) cells. The ethanolic extracts of BJK showed anti-allergic activity (IC50=12.69μg/ml) and exhibited potent NO inhibitory effect (IC50=16.60μg/ml), but inactive on TNF-α release. Moreover, 6-shogaol and plumbagin, two pure compounds from BJK, showed higher anti-allergic activity than the ethanolic BJK extract with IC50 values of 0.28 and 4.03μg/ml, respectively. These compounds were significantly higher than chlorpheniramine (CPM), standard drug, with IC50 value of 17.98μg/ml. Determination of the anti-inflammatory activity by measuring the inhibition of NO production presented that plumbagin and 6-shogaol exhibited higher than crude BJK extract with IC50 values of 0.002 and 0.92μg/ml, respectively. In particular, plumbagin also showed higher anti-inflammatory than prednisolone, positive control, with IC50 value of 0.59μg/ml. 6-Shogaol also showed inhibitory effect on TNF-α release (IC50=9.16μg/ml). These preliminary results may provide some scientific support for the use of BJK for the anti-allergic treatment and inflammatory disorders through the inhibition of NO production.