Background: The Post-Coronary Artery Bypass Graft (CABG) biobehavioral study measured the heart rate (HR) and blood pressure (BP) responses to mental stress testing (MST) after surgery and prospectively observed the clinical events in patients who had undergone recent CABG surgery. To the extent that CABG surgery restores myocardial blood flow and prevents myocardial ischemia, patients who have recently recovered from CABG surgery may have nearly normal HR and BP responses to MST. Methods: A study population of 521 patients (351 men, 170 women) from the cohort of 759 patients in the Post-CABG biobehavioral Study was monitored during a mirror tracing test (MTT) and a speech test task (STT) at the 6-month post-CABG surgery follow-up. Medical status for as long as 3 years after CABG surgery was ascertained from questionnaires and medical records. Results: The HR and BP responses during MTT and STT were similar to those reported in other studies of healthy individuals and patients without myocardial ischemia during MST. In contrast to results from other studies of patients with coronary artery disease, the quartile of Post-CABG biobehavioral study patients with the greatest responses in HR, systolic BP (SBP) and diastolic BP (DBP) during MST had half the rate of clinical events (10% in 3 years) as the quartile (20%) with the lowest changes in HR and BP (HR, P = .01; SBP, P = .07; DBP, P = .01). Conclusions: Vigorous HR and BP responses to MST may be markers for a lower risk of incidence of clinical cardiovascular events among patients who have undergone recent CABG surgery.