Objectives: This study sought to evaluate the 30-day and 1-year safety and performance of the Hydra transcatheter aortic valve (THV) (in the treatment of symptomatic severe aortic stenosis in patients at high or extreme surgical risk. Background: The Hydra THV is a novel repositionable self-expanding system with supra-annular bovine pericardial leaflets. Methods: The Hydra CE study was a premarket, prospective, multicenter, single-arm study conducted across 18 study centers in Europe and Asia-Pacific countries. The primary endpoint was all-cause mortality at 30 days. All endpoints were adjudicated by an independent clinical events committee. Results: A total of 157 patients (79.2 ± 7.1 years of age, 58.6% female; Society of Thoracic Surgeons score 4.7 ± 3.4%) were enrolled. Successful implantation was achieved in 94.3% cases. At 30 days, there were 11 (7.0%) deaths, including 9 (5.7%) cardiovascular deaths, of which 5 (3.2%) were device related. At 1 year, there were 23 (14.6%) deaths, including 13 (8.3%) cardiovascular deaths. At 30 days, there were significant improvement of effective orifice area (from 0.7 ± 0.2 cm² to 1.9 ± 0.6 cm²) and mean aortic valve gradient (from 49.5 ± 18.5 mm Hg to 8.1 ± 3.7 mm Hg), which were sustained up to 1 year. Moderate or severe paravalvular leak was observed in 6.3% of patients at 30 days and 6.9% of patients at 1 year. The rate of new permanent pacemaker implantation was 11.7% at 30 days and 12.4% at 1 year. Conclusions: The Hydra CE study demonstrated that transcatheter aortic valve replacement with Hydra THV offered favorable efficacy at 1 year, providing large effective orifice area and low transvalvular gradient as well as acceptable complication rates with regard to new permanent pacemaker and paravalvular leak. (A Clinical Evaluation of the HYDRA Self Expanding Transcatheter Aortic Valve; NCT02434263)