Abstract: The water soluble fraction (WSF) of the extract of musk exhibited an anti-inflammatory activity which could be shown in various models of experimental inflammation including (1) mouse ear inflammation caused by croton oil, (2) yeast or agar induced paw edema in rats, (3) adjuvant polyarthritis in rats, (4) heat induced increase of permeability in rat skin, and (5) white cell migration in rats.The anti-inflammatory activity of musk-1, a polypeptide isolated from WSF was found to be 36 times more potent than that of hydrocortisone on a weight basis following iv injection in mice as shown in the ear inflammation induced by croton oil; on a molar basis the potency is estimated to be 500 times that of hydrocortisone. The LD₅₀ of WSF was 848 mg/kg after iv injection in mice.