Objective: Genetic factors play a role in pathogenesis of amyotrophic lateral sclerosis (ALS). A few studies demonstrated that the TT genotype of C677T polymorphism of the 5,10- methylenetetrahydrofolate reductase (MTHFR) gene can increase the risk of sporadic ALS. The aim of our study was to determine the relationship between C677T polymorphism of MTHFR gene and the risk of sporadic ALS in Polish population and to perform the metaanalysis assessing the significance this polymorphism for the risk of ALS in Caucasian population. Methods: We included 251 patients with ALS and 500 control subjects recruited from Polish population and performed the meta-analysis of published data from Caucasian population. MTHFR C677T polymorphism was genotyped using a TaqMan assay and 7900HT Fast real Time PCR System. Results: The frequency of genotypes did not differ significantly between Polish ALS patients and control subjects (CC: 45.0 vs 45.8%, CT: 48.2 vs 45.0%, TT: 6.8 vs 9.2%, P = 0.46). The metaanalysis including 863 ALS patients and 1362 controls revealed that TT genotype increases the risk of sporadic ALS in Caucasian population. Conclusion: Although we did not find the association between C677T polymorphism of MTHRF gene and risk of ALS in Polish population, the results of meta-analysis suggest that the TT genotype can be a genetic risk factor for ALS in Caucasian population.