The aim of the study was to verify the association between abdominal aortic aneurysms (AAA) and methylenetetrahydrofolate reductase (MTHFR) mutation, in relation to age. We studied the frequency of the MTHFR 677T allele in two groups of AAA patients, over and under 60 years. The first AAA group included 42 patients (30 men and 12 women) aged between 65 and 75 years; the second AAA group included 46 patients (32 men and 14 women) aged between 49 and 59 years; the control group included 44 healthy controls (29 men and 15 women) aged between 49 and 75 years. We examined MTHFR allele frequency and MTHFR genotype using Nuclear Laser Medicine. MTHFR allele frequency was significantly increased in AAA patients >60 compared to healthy controls and in AAA patients <60 compared to those >60. The genotype study showed a difference between controls and AAA patients and between AAA patients >60 and those <60. The frequency of MTHFR mutation was more elevated in both AAA groups vs controls, but it was more elevated in younger patients than in the older ones. This mutation might induce an early elastin degradation in the aortic wall.