The article relates to investigation of the anti-inflammatory effects of Semecarpus anacardium LINN. nut extract (SA), and also an anti-inflammatory drug, indomethacin, on carrageenan-induced paw edema and cotton pellet granuloma tests for their effects on acute and chronic phases of inflammation, respectively. The effect of SA on developing and developed adjuvant arthritis was also evaluated. SA significantly decreased the carrageenan-induced paw edema and cotton pellet granuloma. Indomethacin also decreased the acute and chronic phases of inflammation. SA decreased the adjuvant induced (arthritis) paw edema after the treatment, in both developing and developed adjuvant arthritis. These results indicate that the potent anti-inflammatory effect and therapeutic efficacy of Semecarpus anacardium LINN. nut extract against all phases of inflammation, is comparable to that of indomethacin.