There is a consensus in the scientific literature that supports the importance of the kallikrein kinin and renin angiotensin systems in renal physiology, but few studies have investigated their importance after renal transplantation. The aim of this study was to investi-gate the clinical effects of the insertion/deletion poly-morphism in the angiotensin I-converting enzyme (ACE) gene and the + 9/-9 polymorphism in the kinin B2 recep-tor (B2R) gene in kidney-transplanted patients (n = 215 ACE, n = 203 B2R) compared with 443 healthy indivi-duals. Demographic results showed that there is a higher frequency of the D allele (high plasma ACE activity) and + 9 allele (lower B2R expression) in transplant patients compared with control individuals. We also observed a higher frequency of these alleles in patients who had an elevated level of plasma creatinine. At day 7 post-trans-plantation, we found a higher prevalence of individuals with the DD genotype with elevated plasma creatinine level. Furthermore, individuals with the DD genotype had a higher chronic allograft dysfunction and graft loss compared with the II patient genotype, which showed no loss of graft. Taken together, our data suggest that the DD genotype is an indicator of an unfavorable prognosis following renal transplantation and could be related to kinin modulation.