Hepatic artery thrombosis (HAT) is the most common vascular complication after liver transplantation; it has been reported to occur in 2% to 5% of liver transplant recipients. Most reports of HAT in the literature describe single-center series with small numbers of patients and lack the power to definitively identify nontechnical risk factors. We used the United Network for Organ Sharing database of adult deceased donor liver transplants from 1987 to 2006 to identify 1246 patients with graft loss from HAT. Univariate and multivariate regression analyses were performed to identify donor and graft risk factors for HAT-induced graft loss. Although most donor predictors of HAT-induced graft loss were surrogates for vessel size, donor age > 50 years was also a significant predictor of graft loss from HAT (relative risk = 1.45, P < 0.001). Furthermore, the risk of graft loss from HAT increased progressively with each decade of donor age > 50 years, such that a 61% increased risk of HAT-related graft loss (relative risk = 1.61, P < 0.001) was associated with donor age > 70 years. A separate analysis of risk factors for early HAT graft loss (<or=90 days) and late HAT graft loss (> 90 days) found that older donor age was associated with increased late HAT graft loss. These findings are of interest in an era of ongoing organ shortages requiring maximum utilization of potential allografts and increasing allocation of older allografts.