Background: Breast cancer is the most common cancer among women. 1 in every 8 women in the United States have a lifetime risk of getting breast cancer. MTHFR is a key enzyme that regulates the folate metabolism which has an important role in DNA synthesis, repair, and methylation. The aim of the current study was to analyze the association between the MTHFR gene C677T (Ala222Val, rs1801133) polymorphism and breast cancer. Patients and Methods: 199 breast cancer patients and 195 healthy controls were included in this study. The MTHFR gene C677T polymorphism was analyzed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) methods. A meta-analysis including 707 breast cancer patients and 880 controls from Turkish populations was also carried out. Statistical analyses were performed using the χ2 test. Results: No statistically significant differences in allele and genotype frequencies were observed between patients and controls (p > 0.05). Although not statistically significant, TT homozygous variants were encountered more frequently in patients than in controls. A statistically significant association was observed between the MTHFR gene C677T polymorphism and the tumor histology of breast cancer patients (p = 0.038). The results of the meta-analysis suggested that there was a high association between breast cancer and the MTHFR gene C677T polymorphism in Turkish populations (p < 0.0001). Conclusion: In our study, we did not find any association between the MTHFR gene C677T polymorphism and breast cancer. However, a meta-analysis of the 6 association studies carried out in Turkish populations with 707 patients and 880 controls showed a significant association between breast cancer and the MTHFR gene C677T polymorphism.