Abstract Objectives to determine the role of carotid artery disease in the pathophysiology of stroke after coronary artery bypass (CABG). Design systematic review of the literature. Results the risk of stroke after CABG was 2% and remained unchanged between 1970–2000. Two-thirds occurred after day 1 and 23% died. 91% of screened CABG patients had no significant carotid disease and had a <2% risk of peri-operative stroke. Stroke risk increased to 3% in predominantly asymptomatic patients with a unilateral 50–99% stenosis, 5% in those with bilateral 50–99% stenoses and 7–11% in patients with carotid occlusion. Significant predictive factors for post-CABG stroke included; (i) carotid bruit (OR 3.6, 95% CI 2.8–4.6), (ii) prior stroke/TIA (OR 3.6, 95% CI 2.7–4.9) and (iii) severe carotid stenosis/occlusion (OR 4.3, 95% CI 3.2–5.7). However, the systematic review indicated that 50% of stroke sufferers did not have significant carotid disease and 60% of territorial infarctions on CT scan/autopsy could not be attributed to carotid disease alone. Conclusions carotid disease is an important aetiological factor in the pathophysiology of post-CABG stroke. However, even assuming that prophylactic carotid endarterectomy carried no additional risk, it could only ever prevent about 40–50% of procedural strokes.