Background. Graft failure risk is highest during emerging adulthood (17-24 years) in kidney and heart transplant. It is unknown whether a similar association exists in liver transplant recipients. Methods. We sought to estimate the relative hazards of graft failure at different current ages, compared with those aged 21 to 24 years.We evaluated 17 181 patients recorded in the Scientific Registry of Transplant Recipients who received a first isolated liver transplant at 40 years or younger (1988-2013) and had 6 months or longer of graft function. We used time-dependent Cox models to estimate the association between current age and failure risk, defined as retransplant or death after graft failure; observation was censored at death with graft function. Results. There were 2540 failures. Absolute graft failure rates were highest in ages 25 to 29 years (3.0/100 person-years). Compared with individuals with the same time since transplantation, those aged 21 to 24 years had significantly higher failure rates than those younger than 17 years and older than 34 years; hazards did not differ for those aged 25 to 29 years (1.03 [0.86, 1.24]) and were lower, but not significantly, for those aged 17 to 20 years (hazards ratio, 0.83; 95% confidence interval, 0.68-1.01) and ages 30 to 34 years (hazards ratio, 0.84; 95% confidence interval, 0.70-1.01). Conclusions. Among young first isolated liver transplant recipients, graft failure risks are highest in the period from 21 to 29 years of age.