Acute kidney injury (AKI) after coronary artery bypass grafting (CABG) is associated with adverse outcomes. This study investigated if already a minimal change of 0 to 0.3 mg/dl in postoperative serum creatinine values was associated with early death and long-term cardiovascular outcomes and death. From the SWEDEHEART registry, we included 25,686 patients who underwent elective, isolated, primary CABG in Sweden from 2000 to 2008. AKI was categorized according to increases in postoperative creatinine values: group 1, 0 to 0.3 mg/dl; group 2, 0.3 to 0.5 mg/dl; and group 3, >0.5 mg/dl. The primary outcome measure was death from any cause. During a mean follow-up of 6 years, there were 4,350 deaths (17%) and 7,095 hospitalizations (28%) for myocardial infarction, stroke, heart failure, or death (secondary outcome). The adjusted odds ratios (95% confidence interval [CI]) for early mortality in AKI groups 1 to 3 were 1.37 (0.84 to 2.21), 3.64 (2.07 to 6.38), and 15.4 (9.98 to 23.9), respectively. For long-term mortality, the corresponding hazard ratios (95% CI) were 1.07 (1.00 to 1.15), 1.33 (1.19 to 1.48), and 2.11 (1.92 to 2.32), respectively. There was a significant association between each AKI group and the composite outcome (HR 1.09, 95% CI 1.03 to 1.15; HR 1.39, 95% CI 1.27 to 1.52; and HR 1.99, 95% CI 1.84 to 2.16, respectively). In conclusion, already a minimal increase in the postoperative serum creatinine level after CABG was independently associated with long-term all-cause mortality and cardiovascular outcomes, regardless of preoperative renal function.