Background- Transcatheter aortic valve replacement (TAVR) has been shown to improve survival compared with standard therapy in patients with severe aortic stenosis who cannot have surgery. The effects of TAVR on health-related quality of life have not been reported from a controlled study. Methods and Results- The Placement of Aortic Transcatheter Valves (PARTNER) trial randomized patients with symptomatic, severe aortic stenosis who were not candidates for surgical valve replacement to TAVR (n=179) or standard therapy (n=179). Health-related quality of life was assessed at baseline and at 1, 6, and 12 months with the Kansas City Cardiomyopathy Questionnaire (KCCQ) and the 12-item Short Form-12 General Health Survey (SF-12). The primary end point was the KCCQ overall summary score (range, 0-100; higher=better). At baseline, mean KCCQ summary scores (35±20) and SF-12 physical summary scores (28±7) were markedly depressed. Although the KCCQ summary score improved from baseline in both groups, the extent of improvement was greater after TAVR compared with control at 1 month (mean between-group difference, 13 points; 95% confidence interval, 8-19; P<0.001) with larger benefits at 6 months (mean difference, 21 points; 95% confidence interval, 15-27; P<0.001) and 12 months (mean difference, 26 points; 95% confidence interval, 19-33; P<0.001). At 12 months, TAVR patients also reported higher SF-12 physical and mental health scores with mean differences compared with standard care of 5.7 and 6.4 points, respectively (P<0.001 for both comparisons). Conclusions- Among inoperable patients with severe aortic stenosis, compared with standard care, TAVR resulted in significant improvements in health-related quality of life that were maintained for at least 1 year. Clinical Trials Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00530894.