The MTHFR C677T mutation has been shown to be associated with venous thrombosis. The role of this mutation in ischemic stroke is unclear. We investigated whether the MTHFR mutation is a risk factor for patients with ischemic stroke in the Black Sea Turkish population or not. We analyzed 30 patients (119 male, 11 female) [median age: 50 years (range: 2878)] with ischemic stroke who had no known predisposition factors for stroke and 242 (182 male, 60 female) healthy controls [median age: 42 years (range: 18-65)]. Detection of the MTHFR C677T mutation was performed by using commercially available allele-specific PCR-ELISA kits. Prevalence of the MTHFR C677T genotype was 49.1% (CT, 45.8%; TT, 3.3%) in controls and 50% (CT, 43.3%; TT, 6.6%) in patients [OR: 1.03, 95% CI (0.45-2.35]). The prevalence of homozygous gene mutation for MTHFR was higher among patients with stroke than control subjects, but this difference was not statistically significant. The MTHFR gene mutation is not a risk factor for ischemic stroke formation in patients from the Black Sea region in Turkey. (C) 2004 Wiley-Liss, Inc.