OBJECTIVES: This study sought to compare all-cause mortality in patients at intermediate surgical risk undergoing transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (SAVR). BACKGROUND: Physicians are selecting "lower" surgical risk patients to undergo TAVI. No clinical data exist about the clinical outcomes of TAVI versus SAVR among intermediate-surgical-risk patients. METHODS: We prospectively enrolled symptomatic patients with severe aortic stenosis who underwent TAVI or SAVR. Propensity-score matched pairs of TAVI and SAVR patients with Society of Thoracic Surgeons (STS) scores between 3% and 8% made up the study population. Primary endpoint was all-cause mortality at 1 year. RESULTS: Between November 2006 and January 2010, 3,666 consecutive patients underwent either TAVI (n = 782) or SAVR (n = 2,884). Four hundred five TAVI patients were matched to 405 SAVR patients. Of matched TAVI patients, 99 (24%) patients had STS scores <3%, 255 (63%) had scores between 3% and 8%, and 51 (13%) had scores >8%. Among patients with STS scores between 3% and 8%, 20 (7.8%) versus 18 (7.1%) patients had died up to 30 days (hazard ratio: 1.12, 95% confidence interval: 0.58 to 2.15, p = 0.74) and 42 (16.5%) versus 43 (16.9%) patients had died up to 1 year (hazard ratio: 0.90, 95% confidence interval: 0.57 to 1.42, p = 0.64) after TAVI and SAVR, respectively. Effects of treatment on 1-year mortality were similar across all subgroups except for sex, with some evidence for a beneficial effect of TAVI in women but not in men (test for interaction p = 0.024). CONCLUSIONS: Cumulative all-cause mortality at 30 days and 1 year was similar among propensity-score matched TAVI and SAVR patients at intermediate surgical risk. (Surgical Replacement and Transcatheter Aortic Valve Implantation [SURTAVI]; NCT01586910).