Data concerning restenosis following successful recanalization of non-acute internal carotid artery occlusion (ICAO) are scarce. This study was conducted to identify the incidence and predictors of restenosis following successful recanalization of non-acute ICAO.We reviewed the incidence of restenosis (defined as >70% restenosis or reocclusion) among 252 consecutive patients with successful recanalization of non-acute ICAO. Baseline, imaging, and surgery-related characteristics were analyzed to assess their association with restenosis. A scoring system was developed to identify high-risk patients for restenosis.During a median follow-up of 12.6 months, restenosis occurred in 56 patients (22.2%), including 39 with reocclusion and 17 with >70% restenosis. The cumulative restenosis rate was 18.0% at 12 months and 24.1% at 24 months. The incidence of stroke was higher in patients with restenosis (25.0% vs 1.5%, P<0.01). Multivariate analysis showed occlusion length (5-10 cm vs <5 cm (hazard ratio (HR) 3.15, 95% confidence interval (95% CI) 1.07 to 9.29); ≥ 10 cm vs <5 cm (HR 5.01, 95% CI 1.73 to 14.49)), residual stenosis ≥30% (HR 3.08, 95% CI 1.79 to 5.30), and internal carotid artery (ICA) wall collapse (HR 1.96, 95% CI 1.12 to 3.44) as independent predictors of restenosis. Point scores proportional to model coefficients were assigned, with scores ranging from 0 to 6. Patients scoring 3-6 had a 4.00 times higher chance of developing restenosis (95% CI 2.35 to 6.79) compared with those scoring 0-2.Nearly one in five patients experienced restenosis following successful recanalization of non-acute ICAO. Occlusion length, residual stenosis ≥30%, and ICA wall collapse were independently associated with restenosis.© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.