Purpose: Red blood cell distribution width (RDW) is a measure of heterogeneity in erythrocyte size; high levels are associated with increased long-term mortality following myocardial infarction, percutaneous coronary intervention (PTCA), and coronary artery bypass grafting (CABG). The objective was to assess whether baseline RDW is predictive of outcome following transcatheter aortic valve implantation (TAVI). Methods: An observational cross-sectional study of all subjects undergoing TAVI implantation in an experienced European institution was conducted. The baseline characteristics and clinical outcomes from a series of 385 patients who underwent TAVI were collected. The study endpoints were defined according to VARC 2. All patients provided written informed consent for the procedure and data collection. Statistical analysis was performed using SPSS version 21.0. Univariate analysis followed by multivariate regression analysis was performed. The following covariants were adjusted for regression analysis: age, sex, body mass index, logistic EuroSCORE, Society of Thoracic Surgeons score, previous MI, CABG, or PTCA, coronary artery disease, hypertension, chronic obstructive pulmonary disease, diabetes mellitus, peripheral vascular disease, chronic kidney disease, cerebrovascular disease, ejection fraction ≤35%, aortic annulus diameter, and sheath size. Results: In univariate analysis RDW was found to be associated with 30 day-mortality (p= 0.022) and all-cause mortality at 1 year (p= 0.015). No significant association was shown between RDW, combined safety end-point, combined efficacy end-point, cardiovascular death at 30 days and cardiovascular death at 1 year. In Cox regression analysis, RDW remained a significant predictor of all-cause mortality at 1 year (odds ratio [OR] 1.15, 95% confidence interval [CI] 1.02-1.29, p= 0.02). Other significant predictors of total mortality were previous PTCA (OR 0.43, 95% CI 0.22-0.86, p= 0.02), BMI (OR 0.87, 95% CI 0.79-0.95, p= 0.002) and logistic Euroscore (OR 1.02, 95% CI 1.01-1.04, p= 0.004). Post-hoc receiver-operating characteristic (ROC) curve analysis was also performed to further analyse the relation between RDW and all-cause mortality at 1 year. RDW levels were found to be significant of total 1-year mortality with an area under curve of 0.62 (95% CI 0.52-0.72, p= 0.015). Conclusions: In the present study we showed for the first time that RDW, an inexpensive and easily measurable laboratory variable which is used routinely in daily clinical practice, is independently associated with all-cause mortality at one year following TAVI implantation.