Abstract Body (Do not enter title and authors here): Background: Nutritional impairment significantly affects physical and cognitive functions, immune response, recovery, and quality of life in the elderly. However, the impact of malnutrition on the prognosis of patients undergoing transcatheter aortic valve replacement (TAVR) remains unclear. Objective: The aim of this study was to investigate whether additional assessment of nutritional status is meaningful in predicting the prognosis of patients undergoing TAVR. Methods and Results: A total of 654 consecutive patients (mean age 83 ± 6 years, 65% female) who underwent TAVR were included. Nutritional status was evaluated at baseline using the prognostic nutritional index (PNI), calculated as follows: [10 × serum albumin (g/dL)] + [0.005 × total lymphocyte count (/mm³)]. The primary endpoint of this study was all-cause mortality, with a median follow-up period of 3.4 years. Kaplan–Meier analysis showed that patients with severe malnutrition, defined as a PNI of <40, had higher mortality rates (log-rank test, P <0.001). Cox multivariate analysis found that PNI was an independent prognostic factor. Furthermore, the Harrell’s C-statistic of the multivariate analysis for predicting mortality improved from 0.666 to 0.715 (P = 0.002) when PNI was added. Cubic spline analysis revealed that a PNI of less than 40 was associated with a steep increase in the hazard ratio for mortality. Conclusion: Evaluating nutritional status in patients undergoing TAVR provides additional information for predicting clinical outcomes, with PNI being a useful predictive indicator.