It has been suggested that carotid endarterectomy for carotid bifurcation disease may be contraindicated in the presence of carotid siphon lesions. This study was undertaken to assess any difference in stroke rate, mortality, or relief of symptoms in patients with and without such "tandem" lesions following elective carotid endarterectomy. Ninety-one bifurcation endarterectomies were performed in 79 patients. The patients were divided into two groups. Group I (44 patients, 47 endarterectomies) had carotid bifurcation stenosis only; group I (35 patients, 44 endarterectomies) had siphon stenosis plus bifurcation stenosis. All patients in both groups who were symptomatic before operation were relieved of their symptoms. In group I there were no intraoperative or perioperative strokes, four late strokes (8.7%), one operate death (2.1%), and no late deaths. Group II patients had two intraoperative strokes (4.5%), three perioperative strokes (6.8%), two late strokes (5.1%), four operative deaths (9.1%), and three late deaths (7.5%). Eighteen of the 35 patients in group II had a greater degree of carotid siphon stenosis than bifurcation stenosis. In this subgroup, there was one operative stroke (5.6%), only perioperative stroke (5.6%), one late stroke (5.9%), one postoperative death (5.6%), and one late death (5.6%). None of these differences were statistically significant. Relief of symptoms was the same in patients with and without tandem carotid lesions, and there was no significantly increased risk of stroke or death following bifurcation endarterectomy in patients with tandem carotid lesions.