The association between cigarette smoking and atherogenesis is well established. Inflammatory cells may participate in atherogenesis via activation of the NADPH oxidase and the subsequent production of reactive oxygen species (ROS), which exacerbates endothelial injury. However, little is known about the ability of cigarette smoke (CS) to modulate NADPH oxidase protein function. In this study, we investigated the ability of a CS extract derived from a high tar cigarette to alter human neutrophil ROS production and the translocation of two NADPH oxidase proteins, p47phox and p67phox. Phorbol ester-induced intracellular and extracellular production of ROS was reduced following CS treatment as measured by enhanced luminol or isoluminol chemiluminescence, respectively, (luminol AUC was reduced by 59%, p < or =0.0001; isoluminol by 49%, p < or =0.001). The phorbol ester-induced phosphorylation and translocation of p47phox from the cytosol to the membrane was not changed by CS treatment but the translocation of p67phox was reduced. Cigarette smoke treatment alone did not provoke neutrophil ROS production. These findings demonstrate that CS treatment reduced agonist-induced human neutrophil ROS production independent of p47phox phosphorylation and translocation from the cytosol to the membrane. However, this inhibition could be attributed to a reduction in translocation of another cytosolic NADPH oxidase protein, p67phox. Although neutrophil-generated ROS have been implicated in the pathogenesis of atherosclerosis, this does not appear to be the mechanism by which CS induces vascular injury.