Recent studies of endothelial cell biology have provided numerous original findings relevant to transplantation. The molecular mechanisms utilized by endothelial cells to regulate cell entry into the parenchyma are becoming more clearly defined. Emerging results have additionally elucidated how endothelial cells interact with and respond to T cells and antibodies specific for transplant antigens. Progress made in deciphering the cellular and molecular basis of endothelial cell-mediated inflammation has the potential to help with the identification of novel therapeutic targets for prolonging graft survival.