Immunomodulatory effects of Semecarpus anacardium LINN. nut milk extract (SA) were investigated in adjuvant induced arthritis by studying the alterations in humoral and cell mediated immune responses and also the anti-inflammatory effects by evaluating the changes in paw edema, tumour necrosis factor (TNF-alpha), nitric oxide and myeloperoxidase activities. Pharmacological studies were also conducted with SA and indomethacin on experimental animals for evaluating the anti-inflammatory, analgesic, antipyretic and ulcerogenic activities. The alterations in the humoral and cell mediated immunity were significantly reverted back to near normal levels on treatment with SA. The drug significantly reduced the elevation in the paw edema, TNF-alpha, nitric oxide and myeloperoxidase levels when compared with adjuvant induced arthritic animals, which shows the anti-inflammatory activity of the drug. SA showed strong anti-inflammatory effects in xylene-induced ear edema and formalin-induced inflammation. In analgesic test, the extract elicited a potential activity on both acetic acid-induced writhing response as well as hot plate test showing its central and peripheral mediated action. The drug also elicited antipyretic action in yeast-induced hyperemia in rats. In addition, the extract did not produce any ulceration on gastric mucosa during ulcerogenic test and did not produce any serious adverse effects. All these effects are nearly similar to the activities of indomethacin except the ulceration where indomethacin produced significant ulceration. From this study, the protective immunological and pharmacological role of SA is demonstrated.