Background: Long-term outcomes after acute kidney injury remain poorly defined. We determined the association between the magnitude of creatinine increase after cardiac surgery and the risk of incident chronic kidney disease (CKD), CKD progression, and death. Methods: We identified 29 388 individuals who underwent cardiac surgery at Veterans Affairs hospitals between November 1999 and September 2005. The magnitude of creatinine increase was defined by the percent change from baseline to peak creatinine levels after cardiac surgery and categorized as none (≤0%) or as class I, (1%-24%), II (25%-49%), III (50%-99%), or IV (≥100%). Cox proportional hazard models were used to examine the association between the magnitude of creatinine increase and outcomes. Results: The relative hazards for outcomes increased monotonically with greater increases in creatinine levels compared with no change in creatinine levels. The relative hazards for adverse outcomes were significantly higher immediately after the creatinine increase and attenuated over time. Three months after surgery, creatinine increase classes I, II, III, and IV were associated with a greater risk of incident CKD (hazard ratios [HRs] 2.1, 4.0, 5.8, and 6.6, respectively; all P<.01), progression of CKD stage (HRs 2.5, 3.8, 4.4, and 8.0; all P<.01), and long-term mortality (HRs 1.4, 1.9, 2.8, and 5.0; all P<.01). At 5 years, the associations were lower inmagnitude: incident CKD (HRs 1.4, 1.9, 2.3, and 2.3; all P<.01), CKD progression (HRs 1.5, 1.7, 1.7, and 2.4; all P<.01), and mortality (HRs 1.0, 1.2, 1.4, and 1.8; all P<.01, except class I). Conclusion: The magnitude of creatinine increase after cardiac surgery is associated in a graded manner with an increased risk of incident CKD, CKD progression, and mortality.