Background: The relationship between pre-surgical distress and diurnal cortisol following surgery has not been investigated prospectively in caregivers of coronary artery bypass graft (CABG) patients before. We aimed to examine the relationship between pre-surgical anxiety and caregiver burden and diurnal cortisol measured 2 months after the surgery in the caregivers of CABG patients. Method: We used a sample of 103 caregivers of elective CABG patients that were assessed 28.86 days before and 60.94 days after patients’ surgery.