Introduction: Selenium is an essential trace element with important antioxidative properties. The aim of this study was to evaluate the relative risk of cardiovascular mortality according to increasing concentrations of selenium and a possible protective effect of high selenium concentrations against oxidative stress in patients with established coronary artery disease. Methods: In this substudy of the prospective Athero Gene survey, 1867 patients were included. These patients could be stratified according to the diagnosis into stable angina pectoris (SAP, n=852), acute coronary syndrome (ACS, n=879) and exclusion of relevant coronary artery disease (NoCAD, n=123). Results: Low selenium concentration is associated with an increased relative risk for cardiovascular mortality. When the collective with ACS is stratified into tertiles of rising selenium concentration, the survival curves according to the Kaplan-Meier-Method (Log-Rank Test: P=0.0001) reveal an adverse outcome. In contrast, in patients with SAP was no association between the selenium concentration and outcome (P=0.35) had been observed. In a fully adjusted Cox proportional hazards model encompassing classical risk factors, medication and laboratory markers, thirds of increasing selenium concentration were associated with a protective effect in patients with ACS (tertiles: HR: 0.362, 95% CI: 0.149–0.878, P=0.025). In a Cox backward-stepwise regression analysis encompassing sixteen variables of cardiovascular risk prediction, one increment increase in selenium concentration decreased the risk of cardiovascular mortality in patients with ACS (HR:0.746, 95%CI: 0.602–0.926; P-Value: 0.008). Conclusion : Increased selenium concentration is related to an improved outcome after the acute event. This data encourages the concept of selenium administration in patients with ACS.