In patients with dilated aortic root, attempts are made to replace the aorta and preserve the leaflets. The tubular Dacron graft used does not have the sinuses of Valsalva, and therefore might adversely affect the leaflets. The effect of the sinuses on stresses in the leaflets was investigated. The finite element models of the tubular aortic root and the root with the sinuses were constructed. The model was loaded with an internal pressure of 80 mmHg, and the stress determined. In the tubular root there was a stress concentration along the leaflet attachment, and the stress reached 0.65 N/mm². In the sinus root there was no stress concentration, and maximum stress was 0.3 N/mm². In the sinus root the leaflet-sinus assembly expanded uniformly, whereas in a tubular root large deformations occurred along the leaflet attachment. Hence, the sinuses of Valsalva play a key role in minimizing stress in the leaflets.