Background: The Ross operation may be the ideal aortic valve replacement in pediatric patients. However, reoperations for replacement of the homograft in the pulmonary position are inevitable. This study determined influencing factors for the development of homograft stenosis and regurgitation in pediatric Ross patients. Methods: Follow-up echocardiograms of 116 children (86 boys) undergoing Ross operations at a mean age, 9.3 ± 4.9 years were analyzed using hierarchic multilevel modeling. Mean duration of the echocardiographic follow-up was 5.3 ± 4.2 years (609 patient-years, 398 examinations). Results: Median homograft diameter z value was 0.3 (range -2.2 to +7.3). Mean homograft pressure gradient at implantation was 5.0 mm Hg with a significant increase of 4.2 mm Hg/y (p < 0.001) within the first 2 years and a steady state thereafter. Older donor age was significantly associated with lower mean pressure gradient at implantation (p = 0.037). Larger z value had no significant influence on the annual increase of pressure gradient (p = 0.87). Mean grade of regurgitation at implantation was 0.9, without significant annual increase (0.02 grade/y, (p = = 0.32). Older recipient (p = 0.005) and donor age (p < 0.0001) were significantly associated with lower mean regurgitation at implantation. Larger z value was associated with a higher annual increase of regurgitation (p = 0.014). Conclusions: Relevant midterm homograft regurgitation is rare in children after the Ross operation. However, a significant annual increase occurs in the pressure gradient that cannot be influenced by larger graft size. Homograft oversizing may lead to a higher annual increase of regurgitation.