We evaluated the impact of genomic polymorphisms in folate-metabolizing, DNA synthesis and DNA repair enzymes on the clinical outcome of 108 patients with myelodysplastic syndromes (MDS) receiving best supportive care (BSC) or azacitidine. A statistically significant association between methylenetetrahydrofolate reductase (MTHFR) 677T/T, thymidylate synthase (TS) 5′-untranslated region (UTR) 3RG, TS 3′-UTR - 6 bp/ - 6 bp, XRCC1 399G/G genotypes and short survival was found in patients receiving BSC by multivariate analysis (P<0.001; P = 0.026; P = 0.058; P = 0.024). MTHFR 677T/T, TS 3′-UTR - 6 bp/ - 6 bp and XRCC1 399G/G genotypes were associated with short survival in patients receiving azacitidine by multivariate analysis (P<0.001; P = 0.004; P = 0.002). We then performed an exploratory analysis to evaluate the effect of the simultaneous presence of multiple adverse variant genotypes. Interestingly, patients with ≥ 1 adverse genetic variants had a short survival, independently from their International Prognostic Scoring System (IPSS) and therapy received. To our knowledge, this is the first study showing that polymorphisms in folate-metabolizing pathway, DNA synthesis and DNA repair genes could influence survival of MDS patients.