Background. Endothelial dysfunction can be detected at early stages of chronic kidney disease. Although endothelial functions improve after successful renal transplantation, renal transplant recipients have still worse endothelial functions compared to healthy subjects. Vitamin D deficiency and high fibroblast growth factor-23 (FGF-23) levels may have a role on endothelial dysfunction in chronic kidney disease patients. The aim of this study is to investigate the association between endothelial functions, vitamin D, and FGF-23 levels in renal transplant recipients.