AIM To assess the association of inter-ethnic vs intra-ethnic marriage with severity of coronary artery disease(CAD) in men undergoing angiography.METHODS We conducted a prospective multicenter,multi-ethnic,cross sectional observational study at five hospitals in Saudi Arabia and the United Arab Emirates,in which we used logistic regression analysis with and without adjustment for baseline differences. RESULTS Data were collected for 1068 enrolled patients undergoing coronary angiography for clinical indications during the period of April 1~(st),2013 to March 30~(th),2014. Ethnicities of spouses were available only for male patients. Of those enrolled,687 were married men and constituted the cohort for the present analysis. Intra-ethnic marriages were reported in 70% and inter-ethnic marriages in 30%. After adjusting for baseline differences,interethnic marriage was associated with lower odds of having significant CAD [adjusted odds ratio 0.52(95%CI:0.33,0.81)] or multi-vessel disease(MVD) [adjusted odds ratio 0.57(95%CI:0.37,0.86)]. The adjusted association with left main disease showed a similar trend,but was not statistically significant [adjusted odds ratio 0.74(95%CI:0.41,1.32)]. The association between interethnic marriage and the presence of significant CAD and MVD was not modified by number of concurrent wives(P interaction > 0.05 for both).CONCLUSION Among married men undergoing coronary angiography,inter-ethnic,as compared to intra-ethnic,marriage is associated with lower odds of significant CAD and MVD. AIM To assess the association of inter-ethnic vs intra-ethnic marriage with severity of coronary artery disease (CAD) in men undergoing angiography. METHODS We conducted a prospective multicenter, multi-ethnic, cross sectional observational study at five hospitals in Saudi Arabia and the United Arab Emirates, in which we used logistic regression analysis with and without adjustment for baseline differences. RESULTS Data were collected for 1068 enrolled patients undergoing coronary angiography for clinical indications during the period April 1 ~ (st), 2013 to March 30 ~ (th), 2014. Ethnicities of spouses were available only for male patients. Of those enrolled, 687 were married men and composed the cohort for the present analysis. Intra-ethnic marriages were reported in 70% and inter-ethnic marriages in 30% . After adjusting for baseline differences, interethnic marriage was associated with lower odds of having significant CAD [adjusted odds ratio 0.52 (95% CI: 0.33, 0.81)] or multi-vessel disease Adjusted odds ratio 0.57 (95% CI: 0.37, 0.86)]. The adjusted association with left main disease showed a similar trend, but was not statistically significant [adjusted odds ratio 0.74 (95% CI: 0.41, 1.32)] . The association between interethnic marriage and the presence of significant CAD and MVD was not modified by number of concurrent wives (P interaction> 0.05 for both) .CONCLUSION Among married men undergoing coronary angiography, inter-ethnic, as compared to intra-ethnic, marriage is associated with lower odds of significant CAD and MVD.