BACKGROUND: Clinical evidence in coronary surgery is usually derived from retrospective, single institutional series. This may introduce significant biases in the analysis of critical issues in the treatment of these patients. In order to avoid such methodological limitations, we planned a European multicenter, prospective study on coronary artery bypass grafting, the E-CABG registry. DESIGN: The E-CABG registry is a multicenter study and its data are prospectively collected from 13 centers of cardiac surgery in university and community hospitals located in six European countries (England, Italy, Finland, France, Germany, Sweden). Data on major and minor immediate postoperative adverse events will be collected. Data on late all-cause mortality, stroke, myocardial infarction and repeat revascularization will be collected during a 10-year follow-up period. These investigators provided a score from 0 to 10 for any major postoperative adverse events and their rounded medians were used to stratify the severity of these complications in four grades. The sum of these scores for each complication/intervention occurring after coronary artery bypass grafting will be used as an additive score for further stratification of the prognostic importance of these events. DISCUSSION: The E-CABG registry is expected to provide valuable data for identification of risk factors and treatment strategies associated with suboptimal outcome. These information may improve the safety and durability of coronary artery bypass grafting. The proposed classification of postoperative complications may become a valuable research tool to stratify the impact of such complications on the outcome of these patients and evaluate the burden of resources needed for their treatment. CLINICAL TRIALS NUMBER: NCT02319083. ; Peer-reviewed ; Publisher Version