Abstract The purpose of this study was to determine the effect of age on the in-hospital mortality of all 30,972 patients undergoing coronary artery bypass graft (CABG) surgery in New York in 1991 and 1992. Mortality rates were relatively low for patients 40–49, 50–59, and 60–64, 65–69, and 70–74 years old (1.10%, 1.65%, 2.17%, 2.76%, and 3.36%, respectively). However, CABG surgery mortality increased rapidly for patients 75 to 79 years old (5.28%) and patients ≥80 years old (8.31%). To examine the independent effect of age on mortality after accounting for the effects of other significant risk factors, a multivariate statistical model was developed to identify the significant independent predictors of mortality. Age emerged as 1 of 24 significant predictors, with age ≥75 demonstrating much higher mortality risk than lesser age. For example, the odds of an 80-year-old patient's dying in the hospital were 3.25 times the odds of a 50-year-old patient's dying in the hospital, assuming all other significant risk factors were identical.