OBJECTIVE Enlargement of the aortic annulus may be required during aortic valve replacement to avoid patient-prosthesis mismatch. We reviewed patients with enlargement of the aortic annulus with the aim of assessing the stability of the procedure by means of echocardiographic and angio-computed tomography studies. METHODS A series of 53 consecutive patients underwent aortic valve replacement and enlargement of the aortic annulus from 1994 to 2012. The mean age was 68 ± 11 years (range, 29-84 years), and 85% (45 patients) were female. The predominant valvular lesion was aortic stenosis. The mean logistic European System for Cardiac Operative Risk Evaluation was 11.2 ± 13.0. Enlargement of the aortic annulus was performed by extending the aortotomy incision to separate the commissure between the left and noncoronary sinuses into the anterior mitral leaflet and closing the resulting defect with an adequately tailored patch of bovine pericardium. RESULTS Hospital mortality was 2%, with 20 late deaths mostly due to noncardiac causes. At a maximum follow-up of 18 years (mean, 8.9 ± 5.0 years), actuarial survival is 37% ± 9%. No cases of severe patient-prosthesis mismatch were observed, and only 2 patients had moderate patient-prosthesis mismatch. At discharge, the mean aortic root diameter was 30.0 ± 2.3 mm and the mean diameter at the sinotubular junction was 31.5 ± 5.0 mm. At follow-up, the mean aortic root diameter was 31.0 ± 3.4 mm and the mean diameter at the sinotubular junction was 31.7 ± 4.5 mm (P = not significant) with no cases of late aneurysm formation on angio-computed tomography. CONCLUSIONS Enlargement of the aortic annulus is a safe and effective procedure and should be indicated in patients with a small aortic annulus; particularly, it should be considered to prevent patient-prosthesis mismatch and its potential deleterious long-term effects.