Cytotoxic T-lymphocyte antigen 4 (CTLA-4) molecule is an important inhibitor of T-lymphocyte response. Polymorphisms in the CTLA-4 gene have been described to be associated with numerous autoimmune diseases. However, similar studies in solid organ transplantation have been scarce. Therefore, we examined the distribution of three single nucleotide dimorphisms, namely, -1147T/C, -318C/T, and +49A/G, in two groups of allogeneic kidney graft recipients: (1) those with at least one acute rejection episode ("rejectors"; n = 38) and (2) those with no signs of acute rejection ("nonrejectors"; n = 53). Allele frequencies in both groups of patients were similar in two positions, -1147T/C and +49A/G. However, rejectors showed slight differences from nonrejectors for allele and genotype frequencies in position -318. The -318T allele was two times less frequent among rejectors than nonrejectors, a difference that was close to statistical significance (P = .039; P corrected = .0583), and may reach it when greater numbers of patients are tested.