Background Progressive dilatation of the pulmonary autograft is the principal cause for reoperation following the Ross procedure when the root replacement technique is used. We examined the relation between enlargement of the pulmonary autograft and the development and progression of neo-aortic valve regurgitation, and the long-term clinical follow-up, including the need for reoperation, in patients followed for up to 13 years postoperatively. Methods A Ross procedure was performed on 119 older children and young adults (mean age: 31 years old), using the root replacement technique, between June 1989 and January 2002. Serial echocardiography studies were obtained in 108 patients and analyzed blinded to clinical data. The following variables were measured: diameter of annulus, sinuses of Valsalva, and supravalvular ridge; presence and severity of aortic regurgitation; and valve thickening. Results The 30 day and late mortality rates were 1.7% and 1.7% (2 patients each). Forty-one patients were followed for more than 5 years, 19 for more than 7 years, and 9 for more than 10 years. There was one thrombotic and no endocarditis events. The 10-year actuarial survival was 96%. Reoperation on the pulmonary autograft or the pulmonary allograft was required in 12 patients. The principal indication for operation on the pulmonary autograft in 11 patients was neo-aortic valve regurgitation (7), aneurysm formation (3), and false aneurysm (1). At 10 years, actuarial freedom from reoperation on the pulmonary autograft was 75%. At last follow-up, 8 of 97 patients without reoperation on the autograft had moderate and none had severe regurgitation of the neo-aortic valve. Independent predictors of progression of neo-aortic valve regurgitation were time from operation, dilatation of the supravalvular ridge, and neo-aortic valve thickening (all p < 0.0002). Freedom from reoperation in the pulmonary allograft at 10 years was 86%. Conclusions Long-term follow-up of patients with the Ross procedure using the root replacement technique indicates excellent survival and low thromboembolic and endocarditis risk. The main limitation is the need for reoperation. The prevalence of severe neo-aortic valve regurgitation is low, however there is a progressive increase in regurgitation and in aortic root diameters. Periodic follow-up with echocardiography is recommended because of the continuing risk of progressive regurgitation of the neo-aortic valve and aneurysm formation.