The prolonged waiting time caused by the lack of donor livers leads to an increasing number of terminally ill patients waiting for lifesaving liver transplantation. To rescue these patients, transplant programs are accepting donor organs from the expanded donor pool, using donors of increasingly older age, as well as from the pediatric age group, often despite significant mismatch in liver size. We investigated the outcome of 102 consecutive liver transplantations using pediatric donor livers in adult recipients. One-year graft survival using donors aged 12 years or younger (group 1, n = 14) and donors aged 12 to 18 years (group 2, n = 88) was compared. In addition, risk factors for graft loss and vascular complications were analyzed. The 1-year graft survival rate in adult transplant recipients in group 1 was 64.3% compared with 87.5% in those in group 2 (P = .015). The main cause of graft loss was arterial complications, occurring in 5 of 16 transplant recipients (31.3%). Major risk factors for graft loss and vascular complications were related to the size of the donor: age, height and weight, body surface area of donor and recipient, and warm ischemic time. We conclude that the outcome of small pediatric donor livers in adult recipients is poor, mainly because of the increased incidence of arterial complications. When a pediatric donor is used in an adult recipient, ischemic time should be kept to a minimum and anticoagulative therapy should be administered in the immediate postoperative period to avoid arterial complications. However, because small pediatric donors are the only source of lifesaving organs for the infant recipient, the use of small pediatric donor livers in adults should be avoided.