In the traditional Indian system of medicine, Ayurveda, several spices and herbs are claimed to possess medicinal properties, such as being antithrombotic, antiatherosclerotic, hypolipidemic, anti-inflammatory etc. Earlier we have reported that extracts from several spices behave as antiaggregatory agents and inhibit eicosanoid synthesis. Similar studies with extracts prepared from cumin (Cuminum cyminum) and turmeric (Curcuma longa) were undertaken. Ethereal extract of both cumin and turmeric inhibited arachidonate-induced platelet aggregation. Extracts from these spices inhibited thromboxane B2 production from exogenous (14C) arachidonic acid (AA) in washed platelets; a simultaneous increase in the formation of lipoxygenase-derived products was observed. Less TxB2 was produced in blood samples treated with turmeric extract when they were allowed to clot. Turmeric extract inhibited incorporation of (14C)AA into platelet phospholipids and deacylation of AA-labelled phospholipids on stimulation with calcium ionophore A23187. Cumin extract was devoid of such effects. Extracts from the two spices reduced the formation of (14C)TxB2 from AA-labelled platelets when they were challenged with A23187. The anti-inflammatory property of turmeric may, in part, be explained by its effect on eicosanoid biosynthesis.