Background: The gold-standard approach to prosthesis sizing before transcatheter aortic valve implantation (TAVI) is multislice computed tomography (MSCT). We aimed to investigate whether conventional aortic root angiography (CA) alone can reliably facilitate valve selection and to describe its inter-reader variability., Methods: Five TAVI specialists (3 interventional cardiologists and 2 cardiac surgeons) independently reviewed preprocedural CAs for 50 patients implanted with the Edwards SAPIEN 3 valve., Results: The prosthesis size selected based on visual CA appraisal matched that based on MSCT in 60% of cases (range: 50%-68%), with undersizing in 11% (4%-33%) and oversizing in 29% (10%-46%; p=0.187 for equality of the proportions test). Agreement between CA-based and MSCT-based valve selection was moderate (K=0.41; Kw=0.61). Reassessment of choice following awareness of the annulus long-axis diameter did not significantly improve this agreement (0.40 and 0.63, respectively), though more undersizing (14%) and less oversizing (25%) occurred. Correct valve selection was more common in interventional cardiologists than cardiac surgeons (66% vs 53%; p=0.0391), who made more oversizing errors., Conclusions: There is a modest agreement between CA-based and MSCT-based SAPIEN 3 selection. Although the former should not be performed routinely, it may be informative in settings where MSCT and transoesophageal echocardiography are unavailable., Competing Interests: Competing interests: SK is a consultant for Jena Valve and Edwards Lifesciences. CT is a consultant for Boston Scientific and receives research support from Edwards Lifesciences and Boston Scientific. PB is a consultant for Abbott, Boston Scientific and Edwards Lifesciences., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)