Aging is a risk factor for atheromatous carotid artery stenosis and also for many cancers. The aim of this study was to explore the relationship between cancer and severe carotid stenosis requiring carotid endarterectomy (CEA). We retrospectively reviewed data obtained from 97 patients (92 men and 5 women; mean age: 76 years) who underwent CEA and were followed for more than six months at our institution. The follow-up period ranged from 6 months to 11 years (mean: 3.6 years). We divided the patients into four groups based on the timing between CEA and cancer: group 1 had a past history of cancer; group 2 underwent CEA during medical treatment for cancer; group 3 underwent CEA before surgery for cancer because severe carotid stenosis was detected by ultrasonography; and group 4 developed cancer after CEA. Five patients died during follow-up after CEA, and three of them died of cancer. Group 1 included 10 patients, among whom five received radiotherapy to the neck. CEA was performed safely in this group. Group 2 comprised two patients (one each with esophageal cancer and bilateral parotid cancer). Group 3 also included two patients, both of whom had colon cancer and severe carotid stenosis detected by ultrasonography before cancer surgery. They underwent laparoscopic tumor resection soon after CEA while off of antiplatelet medication. Group 4 had a total of eight patients. None of the patients developed ischemic stroke during surgery after stopping antiplatelet medication. In Japan, the population is aging rapidly, so the relationship between cancer and carotid stenosis will become more important over time. We identified the following points about the relationship between CEA and cancer from our experience: 1) CEA should be performed with the assumption that the patient will undergo cancer surgery in the future. 2) As ultrasonography becomes more common, detection of asymptomatic severe carotid stenosis may increase, necessitating decisions about the order of and method for treating both carotid stenosis and cancer. 3) CEA can be performed safely even after irradiation of the neck in our experience. 4) CEA was also performed safely in one patient with massive bilateral parotid tumors.