Increased arterial stiffness is associated with atherosclerosis in humans, but there have been limited animal studies investigating the relationship between these factors. We bred elastin wildtype (Eln^+/+) and heterozygous (Eln^+/−) mice to apolipoprotein E wildtype (Apoe^+/+) and knockout (Apoe^−/−) mice and fed them normal diet (ND) or Western diet (WD) for 12 weeks. Eln^+/− mice have increased arterial stiffness. Apoe^−/− mice develop atherosclerosis on ND that is accelerated by WD. It has been reported that Apoe^−/− mice have increased arterial stiffness and that the increased stiffness may play a role in atherosclerotic plaque progression. We found that Eln^+/+Apoe^−/− arterial stiffness is similar to Eln^+/+Apoe^+/+ mice at physiologic pressures, suggesting that changes in stiffness do not play a role in atherosclerotic plaque progression in Apoe^−/− mice. We found that Eln^+/−Apoe^−/− mice have increased structural arterial stiffness compared to Eln^+/+Apoe^−/− mice, but they only have increased amounts of ascending aortic plaque on ND, not WD. The results suggest a change in atherosclerosis progression but not end stage disease in Eln^+/−Apoe^−/− mice due to increased arterial stiffness. Possible contributing factors include increased blood pressure and changes in circulating levels of interleukin-6 (IL6) and transforming growth factor beta 1 (TGF-β1) that are also associated with Eln^+/− genotype.