CTLA4 is expressed on the surface of T helper cells and has a suppressive role in the lymphocytes' activation process. It transmits an inhibitory signal to T cells. Studies suggest that the rate of CTLA4 synthesis has a genetic background. There are several polymorphisms of the CTLA4 gene that can influence the expression of this molecule and may therefore affect immune response and allograft function after kidney transplantation. The aim of this study was to examine the impact of the rs231775 (+49AG) CTLA4 gene polymorphism on transplanted kidney function.The study enrolled 269 Caucasian renal transplant recipients (166 males, 103 females, mean age 47.63±12.96 years). Genotyping of the rs231775 (+49AG) CTLA4 gene polymorphism was performed using real-time PCR.The frequency of DGF was higher in the individuals with the G allele of the rs231775 (+49AG) CTLA4 gene polymorphism compared with the carriers of the A allele (GG+AG vs. AA, OR 1.80; 95% CI 1.02-3.18, p=0.05). In multivariate analysis, rs231775 CTLA4 gene polymorphism G allele was an independent factor associated with increased risk of DGF (p=0.03).Rs231775 (+49AG) CTLA4 gene polymorphism may be associated with increased risk of delayed graft function after kidney transplantation.