Background: Carotid lesions will often remain asymptomatic during the perioperative period, so prophylactic carotid endarterectomy (CEA) has not been advocated before other operations. The purpose of this study was to characterize the clinical manifestations of new neurologic symptoms occurring in patients with previously asymptomatic carotid occlusive disease who have undergone recent operations. Study design: We performed a retrospective review of patients developing neurologic symptoms attributable to carotid occlusive disease after unrelated operations. Results: Eleven patients (mean age 68 ± 6.4 years, 8 men, 3 women) developed new neurologic symptoms from previously asymptomatic extracranial carotid stenoses after 11 unrelated procedures. Neurologic events included hemispheric stroke (n = 10) and amaurosis fugax (n = 1). Two intraoperative strokes occurred (one mastectomy, one prostatectomy). Other events occurred a mean of 5.8 ± 5 (range 1 to 16) days after aortic surgery (n = 2), infrainguinal bypass (n = 3), contralateral CEA for symptomatic disease (n = 2), incisional herniorrhaphy (n = 1), and prostate surgery (n = 1). Responsible internal carotid artery lesions were all stenoses greater than 80%; seven were clearly greater than 90%. Those suffering intraoperative stroke or stroke within 24 hours of operation (n = 3) were not receiving antithrombotic therapy. All other events (n = 8) occurred despite the use of antiplatelet or anticoagulant agents. Four underwent emergent CEA. Four had elective CEA performed after reaching a neurological recovery plateau. Conclusions: Critical, asymptomatic internal carotid artery stenoses may cause neurologic symptoms after unrelated surgical procedures.