The anti-inflammatory effect of an ethanol extract of Helicteres gardneriana (Nees) Castiglioni was assayed in experimental models of pleurisy and microcirculation in situ. Treatment of animals with 500 mg/kg body weight reduced the exudate volume (35% reduction) induced by intrapleural injection of carrageenan and the migration of polymorphonuclear cells into the inflamed pleural cavity of rats (40%). Additionally, rolling and adhesion of leukocytes and the number of leukocytes that migrated toward the perivascular space in response to the carrageenan injection were decreased by the extract (500 mg/kg). These data demonstrate the anti-inflammatory effect of the ethanol extract of Helicteres gardneriana and imply that inhibition of leukocyte-endothelial interactions is important in the extract's mechanism of action.