The pooled results of nine studies showed that MTHFR C677T variant and T-allele expression increased the risk of ischemic stroke remarkably consistently as follows: CT + TT versus CC, OR 1.23, 95%CI 1.06–1.43, P = 0.0067, Fig. 2a; CT versus CC, OR 1.18, 95%CI 1.01–1.38, P = 0.0333, Fig. 2b; TT vs. CC: OR 1.41, 95%CI 1.14–1.75, P = 0.0016, Fig. 2c; TT vs. CC + CT: OR 1.27, 95%CI 1.05–1.54, P = 0.0145, Fig. 2d; T-allele versus C-allele: OR 1.18, 95%CI 1.06–1.31, P = 0.0023, Fig. 2e. This evidence concerns the gene MTHFR and ischemic stroke.