the functional effect of the a>g transition at position 2756 on the mtr gene (5-methyltetrahydrofolate-homocysteine methyltransferase), involved in folate metabolism, may be a risk factor for head and neck squamous cell carcinoma (hnscc). the frequency of mtr a2756g (rs1805087) polymorphism was compared between hnscc patients and individuals without history of neoplasias. the association of this polymorphism with clinical histopathological parameters was evaluated. a total of 705 individuals were included in the study. the polymerase chain reaction-restriction fragment length polymorphism technique was used to genotype the polymorphism. for statistical analysis, the chi-square test (univariate analysis) was used for comparisons between groups and multiple logistic regression (multivariate analysis) was used for interactions between the polymorphism and risk factors and clinical histopathological parameters. using univariate analysis, the results did not show significant differences in allelic or genotypic distributions. multivariable analysis showed that tobacco and alcohol consumption (p < 0.05), ag genotype (p = 0.019) and g allele (p = 0.028) may be predictors of the disease and a higher frequency of the g polymorphic allele was detected in men with hnscc compared to male controls (p = 0.008). the analysis of polymorphism regarding clinical histopathological parameters did not show any association with the primary site, aggressiveness, lymph node involvement or extension of the tumor. in conclusion, our data provide evidence that supports an association between the polymorphism and the risk of hnscc.