Verbascum mallophorum is part of a large family of Scrophulariaceae consisting of more than 360 species. Verbascum mallophorums contains diverse polysaccharides, iroid glycosides, flavonoids, saponins, volatile oils and phenylentanoids. Verbascum has been used in popular medicine for treating wounds, chilblains, respiratory ailments, acne and arthritic disturbances. Inducible nitric oxide synthase (iNOS) represents one of the three isoforms that produce nitric oxide using L-arginine as a substrate in response to an increase in superoxide anion activated by NF-kappaB. It is implicated in different pathophysiological events and its expression increases greatly during an inflammatory process due to oxidative stress. In our study we reproduced an inflammatory state by treating THP-1 cells (human myelomonocytic leukaemia) with pro-inflammatory stimuli, such as LPS and IFN-gamma, obtaining an up-regulation both in the expression and in the activity of iNOS. The aim of our work is to investigate the possible antiinflammatory action of verbascoside extract from Verbascum mallophorum using a concentration of 100 muM. Our results show a significant decrease in the expression and activity of iNOS and extracellular O2- when cells were treated with verbascoside. Based on these results we hypothesize that verbascoside extract from Verbascum mallophorum has anti-inflammatory properties since it reduces the production of superoxide radicals and consequently reduces the activity of iNOS.