Appropriate sizing of the Perceval valve (Corcym, London, UK) can pose a challenge, especially for the surgeon who is just embarking on adopting this valve into practice. Correct or “right” sizing of Perceval valves is important if one is to reap the benefits of the superior hemodynamic performance, shorter operative times, and excellent clinical outcomes that this valve offers. 1 – 7 The Perceval valve has a nitinol frame and bovine pericardial leaflets. Nitinol has 2 distinct properties: shape memory