Heart rate (HR) predicts mortality and cardiovascular events in the general population and in patients with coronary artery disease. However, little evidence is available for patients after coronary revascularization. The aim of this study was to assess the prognostic value of ambulatory postoperative HR after coronary artery bypass grafting. Data from a prospective cohort study enrolling patients who underwent nonurgent coronary artery bypass grafting from 1998 to 2002 were analyzed. Baseline postoperative HR was measured 2 months after surgery, and patients were followed annually thereafter. The primary outcome was all-cause mortality. The secondary outcome combined any of the following events: death, nonfatal acute coronary syndromes, stroke or transient ischemic attack, secondary coronary revascularization, or vascular surgery. Seven hundred ninety-four patients (mean age 65.8 ± 9.3 years) were eligible for follow-up, predominantly men (84.1%). The mean follow-up duration was 3.2 ± 1.3 years, during which 40 patients (5.0%) died. In the univariate analysis, HR >90 beats/min was significantly associated with all outcomes. After adjustments for major confounding factors and the use of β blockers, postoperative HR >90 beats/min remained significantly associated with the secondary outcome (hazard ratio 2.26, 95% confidence interval 1.04 to 4.91, p = 0.04). Association of postoperative HR >90 beats/min with all-cause mortality was only borderline in the multivariate analysis (hazard ratio 3.57, 95% confidence interval 0.90 to 14.17, p = 0.07), because of the limited sample population size. In conclusion, postoperative HR >90 beats/min may be associated with poor prognoses in patients with coronary artery disease, even after surgical revascularization.