We aimed to evaluate the long-term outcome of carotid endarterectomy (CEA) and carotid artery stenting (CAS) in patients who underwent both procedures on different sides. In this single-center retrospective study (2001-2019), 117 patients (men, N = 78; median age at CEA, 64.4 interquartile range {IQR}, 57.8-72.2 years; median age at CAS, 68.8 IQR, 61.0-76.0 years) with ≥50% internal carotid artery stenosis who had CEA on one side and CAS on the other side were included. The risk of restenosis was estimated by treatment adjusted for patient and lesion characteristics. Neurological symptoms were significantly more common (41.9% vs 16.2%, P<0.001) and patients had a significantly shorter mean duration of smoking (30.2 standard deviation {SD}, 22.2 years vs 31.8 SD, 23.4 years, P<0.001), hypertension (10.1 SD, 9.8 years vs 13.4 SD, 9.1 years, P<0.001), hyperlipidemia (3.6 SD, 6.6 years vs 5.0 SD, 7.3 years, P = 0.001), and diabetes mellitus (3.9 SD, 6.9 years vs 5.7 SD, 8.9 years, P<0.001) before CEA compared to those before CAS. While the prevalence of heavily calcified stenoses on the operated side (25.6% vs 6.8%, P<0.001), the incidence of predominantly echogenic/echogenic plaques (53.0% vs 70.1%, P = 0.011) and suprabulbar lesions (1.7% vs 22.2%, P<0.001) on the stented side was significantly higher. Restenosis rates were 10.4% at 1 year, 22.3% at 5 years, and 33.7% at the end of the follow-up (at 11 years) for CEA, while these were 11.4%, 14.7%, and 17.2%, respectively, for CAS. Cox regression analysis revealed a significantly higher risk of restenosis (hazard ratio HR, 1.80; 95% confidence interval CI, 1.05-3.10; P = 0.030) for CEA compared to that for CAS. After adjusting for relevant confounding factors (smoking, hypertension, diabetes mellitus, calcification severity, plaque echogenicity, and lesion location), the estimate effect size materially did not change, although it did not remain statistically significant (HR, 1.85; 95% CI, 0.95-3.60; P = 0.070). Intra-patient comparison of CEA and CAS in terms of restenosis tilts the balance toward CAS.