Patients with extracranial cerebrovascular disease and peripheral vascular disease are at increased risk of ischaemic heart disease with resulting increased risk of early and late mortality following vascular reconstruction. Over a two year period, 67 patients undergoing carotid or aortic surgery were investigated preoperatively with dipyridamole-thallium scan. There were three positive scans in the first 17 patients; two of these patients suffered a postoperative myocardial infarction (one fatal), compared to none of 14 who had a negative scan (p = 0.02). There were seven positive scans in the next 50 patients. Patients with left main trunk or triple vessel disease were recommended to have coronary artery bypass prior to or combined with the vascular reconstruction. There were no deaths or postoperative myocardial infarction in this group, this improvement in morbidity being statistically significant (p = 0.01). Dipyridamole-thallium scanning is an effective screening procedure for coronary artery disease. Patients with a positive scan are at increased risk of postoperative myocardial infarction following vascular reconstruction. Further investigation with coronary arteriography prior to vascular reconstruction is recommended in patients with positive scans. Coronary artery bypass should be performed prior to or combined with the vascular reconstruction in patients with left main trunk or triple vessel disease.