In adult liver transplant recipients, the donor body mass index (dBMI) is associated with posttransplant obesity but not with graft or patient survival. Because of the obesity epidemic in the United States and the already limited supply of liver donors, clarifying whether the dBMI affects pediatric outcomes is important. United Network for Organ Sharing data for pediatric liver transplants in the United States (1990-2010) were evaluated. Data on transplants performed between 2004 and 2010 (n = 3788) were used for survival analyses with Kaplan-Meier and Cox proportional hazards models and for posttransplant obesity analyses with generalized estimating equations. For children receiving adult donor livers, a dBMI of 25 to <35 kg/m2 was not associated with graft or patient survival in univariate or multivariate analyses. A dBMI ≥ 35 kg/m2 increased the risk of graft loss [hazard ratio (HR) = 2.54, 95% confidence interval (CI) = 1.29-5.01, P = 0.007] and death (HR = 3.56, 95% CI = 1.64-7.72, P = 0.001). For pediatric donors, the dBMI was not associated with graft loss or mortality in a univariate or multivariate analysis. An overweight or obese donor was not a risk factor for posttransplant obesity. Overweight and obesity are common among liver transplant donors. This analysis suggests that for adult donors, a body mass index (BMI) of 25 to <35 kg/m2 should not by itself be a contraindication to liver donation. Severe obesity (BMI ≥ 35 kg/m2) in adult donors increased the risk of graft loss and mortality, even after adjustments for recipient, donor, and transplant risk factors. Posttransplant obesity was not associated with the dBMI in this analysis. Further research is needed to clarify the impact of donor obesity on pediatric liver transplant recipients. Liver Transpl, 2012. © 2012 AASLD.