Increases in creatinine level following cardiac surgery are common; however, it is unknown how these changes influence long-term outcomes. This study uses data on 29 388 veterans undergoing cardiac surgery to determine the association between the magnitude of creatinine level increase following cardiac surgery and incident chronic kidney disease (CKD), CKD progression, or death. Overall, the relative hazards for outcomes increased monotonically with greater increases in creatinine level. Creatinine level increases of 1% to 24%, 25% to 49%, 50% to 99%, or 100% or greater were associated at 3 months with a greater risk of incident CKD (hazard ratio [HR], 2.1, 4.0, 5.8, and 6.6, respectively; all P < .01), progression of CKD stage (HR, 2.5, 3.8, 4.4, and 8.0, respectively; all P < .01), and long-term mortality (HR, 1.4, 1.9, 2.8, and 5.0, respectively; all P < .01) compared with no increase in creatinine. Individuals with increases in creatinine level following cardiac surgery are at risk for long-term adverse outcomes.