Aims: Aging is associated with cognitive deterioration, and genetic factors are implicated in individual cognitive differences in the aged. The C677T mutation in the 5,10-methylenetetrahydrofolate reductase gene (MTHFR) yields a common thermolabile variant (T) with reduced enzyme activity and consequent elevation of serum homocysteine concentrations. We designed the present study to investigate whether this functional polymorphism may affect global and specific cognitive functions in older Chinese males without dementia. Methods: The subjects included 356 elderly males without major psychiatric disorders or dementia, who were assessed by the Cognitive Abilities Screening Instruments (CASI) and the Wechsler Digit Span Task tests. Results: A significant association was found between the MTHFR C677T polymorphism and total CASI scores (p = 0.012), particularly in short-term memory (p = 0.002) and concentration/mental manipulation (p = 0.007). Post hoc tests indicated that the C/T heterozygotes achieved better cognitive function test results than C/C or T/T carriers. No association was found between the MTHFR genotype and the Wechsler Digit Span Task tests. Conclusion: These results suggest that a heterozygote advantage exists for the MTHFR C677T polymorphism in specific cognitive functions in elderly Chinese males without dementia.