ABSTRACT Purpose Methylenetetrahydrofolate reductase (MTHFR) is an enzyme involved in endothelial nitric oxide synthase (eNOS) coupling and homocysteine metabolism. The rs1801133 polymorphism of the MTHFR gene affects risk of coronary artery disease. We assessed its influence on 5-year survival of patients with ST-elevation acute myocardial infarction (STEMI). Material/Methods The study group comprised consecutive patients with STEMI. Genotyping was performed with a TaqMan SNP Genotyping Assay using the ABI 7500 Real Time PCR System (Applied Biosystems). The analyzed end-point was all-cause 5-year survival. Results The study group comprised 637 patients (mean age 62.3±11.9 years; 25.1% females, n=160; 5-year mortality 16.3%, n=104). The percentages of TT, CT and CC genotypes were: 10.8 (n=69), 39.7 (n=253) and 49.45 (n=315), respectively. No significant differences in clinical characteristics were identified between the genotypes (p>0.05 for all parameters). Eleven (15.9%) TT homozygotes, 40 (15.8%) heterozygotes and 53 (16.8%) CC homozygotes died during follow up (p=0.99 log-rank test). TT homozygotes presented only weak and insignificant tendency towards higher mortality rates in subgroups of patients ≤75 years old (15.6 vs. 11.54%, p=0.35) or with intermediate risk according to the GRACE risk score (13.3% vs. 8.76%, p=0.42). Conclusions The rs1801133 polymorphism did not show significant association with 5-year survival.