Reactive oxygen species (ROS) are involved in the pathogenesis of atherosclerosis and coronary artery disease (CAD). NADPH oxidases are the main source of ROS in the vasculature. p22phox is a critical component of vascular NADPH oxidases and is encoded by the CYBA (cytochrome b245 alpha) gene. The -930A>G CYBA polymorphism (rs9932581:A>G) modulates the activity of the CYBA promoter, and influences CYBA transcriptional activity. The aim of the present study was to analyze a possible association between the -930A>G polymorphism and CAD and to search for gene-traditional risk factors interactions. 480 subjects were studied: 240 patients with premature CAD, 240 age and sex matched blood donors. The -930A>G polymorphism was genotyped using the TaqMan® Pre-designed SNP Genotyping Assay (Applied Biosystems). The -930G allele carrier state was a risk factor for CAD (OR 2.03, 95% CI 1.21-3.44, P=0.007). A synergistic effect of the -930G allele with overweight/obesity (BMI≥25) and cigarette smoking was found. The estimated CAD risk for BMI≥25 and the -930G allele interaction was about 160% greater than that predicted by assuming additivity of the effects, and about 40% greater for interaction of cigarette smoking and the -930G allele. Overweight/obesity was a risk factor for CAD only in the -930G allele carriers (P<10(-10)) but not in the AA homozygotes (P=1.00). In conclusion the -930A>G CYBA polymorphism is associated with CAD in the Polish population. The -930G allele carriers are particularly at risk of consequences of obesity and tobacco smoke exposure.