BACKGROUND: Malnutrition is a poor prognostic factor in a wide range of diseases. Nevertheless, there is a lack of data investigating the association between malnutrition and outcomes of patients with type B aortic dissection (TBAD) undergoing thoracic endovascular aortic repair (TEVAR). Therefore, the aim of the present study was to report the prevalence and clinical impact of malnutrition assessed by the controlling nutritional status (CONUT) score in TBAD patients undergoing TEVAR. METHODS: The retrospective study indicated that a total of 881 patients diagnosed with TBAD and treated with TEVAR from January 2010 to December 2017 were categorized into subgroups based on their CONUT score (low 5 . high 5). To assess the correlation between malnutrition and early and follow-up outcomes of TBAD patients, logistic and Cox regression analysis were utilized, incorporating inverse probability weighting. RESULTS: Malnutrition was present in 20.3% of patients according to the CONUT score. Multivariate logistic regression analysis revealed that pre-operative CONUT score modeled as a continuous variable was an independent risk factor for prolonged intensive care unit stay (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.02-1.17; = 0.015), 30-day death (OR, 1.43; 95% CI, 1.19-1.72; 0.001), delirium (OR, 1.11; 95% CI, 1.01-1.23; = 0.035) and acute kidney injury (OR, 1.09; 95% CI, 1.01-1.16; = 0.027). During a median follow-up of 70.8 (46.1-90.8) months, 102 (11.8%) patients died (high CONUT group: 21.8% . low CONUT group: 9.0%; 0.001). Multivariable Cox proportional-hazards models showed that malnutrition was an independent predictor for follow-up mortality (hazard ratio, 1.68; 95% CI, 1.11-2.53; = 0.014). Results remained consistent across various sensitivity analyses. CONCLUSIONS: Malnutrition assessed by the CONUT score could profoundly affect the early and follow-up prognosis in patients undergoing TEVAR. Routine pre-intervention nutritional evaluation might provide valuable prognostic information.