Mammographic breast arterial calcifications (BACs) are regarded as aging-related benign changes in breast cancer screening practices. BACs have recently attracted attention, because several researchers proposed using them as a surrogate marker of arteriosclerosis or osteoporosis. No studies have thus far evaluated an association between BACs and breast cancer, however. The percentage of BAC positivity was compared between a group of women aged 40years or older with breast cancer detected in 2004 through 2009, and a group of women of the same age range in whom breast cancer was not detected by screening mammography in 2009. The BAC-positive rate in the group of 243 breast cancer patients was 9.88% (24 of the 243) and was lower than that in the group of women without breast cancer, 14.34% (506 of 3528 women). The analysis by age revealed that the differences in this parameter between the two groups were significant in women aged 60years or older. Multivariate analysis including demographic characteristics revealed that when adjusted for age and body weight, BAC positivity was a significant risk factor for breast cancer. The study results suggest that BAC positivity and, in turn, arteriosclerosis may have an antinomic relationship with breast cancer.