IMPORTANCE: Today's coronary artery bypass grafting (CABG) population appears to comprise sicker patients than in the past; however, little is known about the change in the risk profile. OBJECTIVE: To evaluate the change with time in the risk profile of patients who undergo CABG. DESIGN, SETTING, AND PARTICIPANTS: Retrospective review of records from the Veterans Affairs (VA) Surgical Quality Improvement Program (VASQIP); 65 097 patients who underwent isolated primary CABG from October 1, 1997, to April 30, 2011, were evaluated. MAIN OUTCOMES AND MEASURES: Trends in risk profiles, surgical volume, and modern outcomes in the VA system.We determined the significance of changes in age and major comorbidities across time with simple linear regression analysis and evaluated the rates of perioperative mortality (30-day or in-hospital) and VASQIP predicted risk of mortality trends over time. RESULTS: From 1997 to 2011, there were increases in mean (SD) patient age (63.1 [9.4] vs 64.3 [7. 8] years; R2 = 0.34; P =.02) and body mass index (28.3 [5.1] vs 30.1 [5.8]; R2 = 0.95). There were also increases in the prevalence of diabetes mellitus (32.8%vs 41.3%; R2 = 0.82), preoperative New York Heart Association (NYHA) class III or IV heart failure status (14.3%vs 34.2%; R2 = 0.74), and left main coronary artery disease (26.0% vs 32.8%; R2 = 0.82) (all P <.001). There was a decrease in the prevalence of advanced angina severity (Canadian Cardiovascular Society class III or IV) (R2 = 0.95), previousmyocardial infarction (R2 = 0.82), and low ejection fraction (≤34%) (R2 = 0.88) (all P<.05). There was no significant change in the prevalence of cerebrovascular and peripheral vascular disease, chronic obstructive pulmonary disease, or 3-vessel coronary artery disease. Perioperative mortality rates and the VASQIP predicted risk of mortality, respectively, decreased with time (3.2%and 3.1% vs 1.7% and 1.6%). From 2004 to 2011, there was a significant increase in the prevalence of previous percutaneous coronary intervention (18.6%to 29.2%; R2 = 0.82; P =.002). Overall CABG volume decreased (5551 in 1998 vs 3857 in 2012; R2 = 0.95; P<.001). CONCLUSIONS AND RELEVANCE: From 1997 to 2011, there was a progressive increase in the prevalence of obesity, diabetes, left main coronary artery disease, and advanced NYHA heart failure class among VA patients undergoing CABG. The prevalence of previousmyocardial infarction, low ejection fraction, and advanced angina decreased, perhaps because of earlier surgical referral, improvement in medical management, or a shift in patient selection for CABG. Operative mortality also decreased with time. These trends confirm the general perception of significant, ongoing improvement in the care of patients who undergo CABG in the VA, despite an older, sicker population.