The purpose of this study was to describe mortality during the 2-year-period after coronary artery bypass surgery (CABG) in relation to perioperative risk factors and urgency of operation. All the patients in western Sweden were included in whom CABG was performed between June 1988 and June 1991, without concomitant procedures or re-operations. The study was prospective in design. In all, 2000 patients were operated upon and 186 (9.3%) of the operations were acute. There was a significant relationship between the urgency of the operation and mortality. Early mortality was 2.4% in elective operations and 5.4-62.5% in urgent to emergency operations. The 30-day to 2-year mortality was 4.2%. The perioperative risk indicators independently associated with early mortality were neurologic complications, serum-aspartate aminotransferase (S-ASAT) more than 2.0 microkat/l, urgency of operation, the use of circulatory assist devices, re-operation and ventilator time more than 24 h. The risk indicators for mortality after 30 days were pneumothorax, longer intensive care unit (ICU) time, the use of inotropic drugs and neurologic complications. In conclusion, the multivariate analysis reveals the urgency of the operation as a predictor of early mortality after CABG, but no significant association with mortality was found after 30 days. When excluding death within 30 days, three additional independent predictors of mortality were identified.