The genetic background may modify the individual's risk of developing cancer. We performed a case-control study to test the impact of genomic polymorphisms of 9 genes involved in xenobiotics detoxification and DNA repair in myelodysplastic syndromes (MDS). Frequencies of polymorphic variants of RAD51, XRCC3, NQO1, GSTA1, GSTM1, GSTT1, CYP3A4 and XPD enzymes were similar in patients and controls. On the other hand, the GSTP1-105Val allele was associated to an increased risk of MDS (O.R. 1.66; p=0.04) and to higher probability of overall survival in the low/intermediate-1 IPSS risk group (p=0.008). The GSTP1-Ile105Val polymorphism is likely to influence MDS risk and prognosis.