Background and objectives: The small aortic annulus is a major problem facing surgeons performing aortic valve replacement. There are two options: either to replace the valve with a 19 mm prosthesis, or to perform aortic root enlargement procedure to insert a larger valve. The aim of the study was to compare the advantages and disadvantages of aortic valve replacement with a small prosthesis to that with aortic root enlargement. Methodology: Forty patients with aortic valve disease having a small aortic annulus will be randomized into two groups: group A will undergo aortic valve replacement with a 19 mm valve, and group B will undergo aortic root enlargement with insertion of a larger valve. The mean age for group A was 34 years, and the mean age for group B was 36.5 years. Standard aortic and common atrial cannulation with antegrade selective cardioplegia was adopted in both groups. Results: There was no statistical difference between the two groups preoperatively regarding their age, sex, NYHA Class, pathology of the valve, LV function and LV dimensions. There was a single post-operative mortality in group B. The post-operative blood loss was more in group B. The post-operative gradient across the valve was significantly less in group B. Conclusion: Aortic root enlargement enables the insertion of a large prosthesis and thus lowers the post-operative gradient across the valve and so it is recommended in cases of small aortic annulus to avoid the insertion of a small prosthesis which can lead to patient/prosthesis mismatch.