Background . Autografts (AG) and homografts (HG) are currently considered the best choices for replacement of the diseased aortic valve in young adults, although few data exist comparing their late outcome. Nonhomogeneous populations and evolving operative techniques confound existing comparisons. Methods . To help clarify these issues, we reviewed our results with 238 hospital survivors (aged 17 to 82 years) undergoing operation between 1986 and 1999. All operations were done as root replacements, and patients needing concomitant valve replacement were excluded. Results . Mean age of the 145 AGs and 93 HGs was 35 ± 13 years and 49 ± 17 years, respectively ( p p = 0.001), and active endocarditis was present at time of current operation in 10 (7%) AG and 25 (27%) HG patients ( p = 0.001). Maximum follow-up was 12.2 years for AGs and 12.8 years for HGs. Late survival at 10 years was 77% ± 11% for AGs and 67& ± 9% for HGs ( p = 0.13). Freedom from AG or HG degeneration at 10 years was 97% ± 2% and 79% ± 10% ( p = 0.63). Freedom from valve-related complications at 10 years was 73% ± 10% and 64% ± 10% ( p = 0.93), respectively. Freedom from all reoperations at 10 years was 88% ± 5% for AG and 72% ± 11% for HG ( p = 0.67). Conclusions . Autografts and HGs have comparable late survival. The incidence of valve degeneration is low for both AG and HG up to about 8 years at which point there may be a trend toward an advantage for AG over the HG, suggesting benefit for the younger patient.