The etiology of breast cancer remains largely unclear, however, it is well known that the incidence of this disease increases with age. In the presented work, for the first time, the age-related changes of Al, As, B, Ba, Bi, Cd, Ce, Cr, Cu, La, Li, Mg, Mn, Nb, Ni, Pb, Rb, Sb, Sn, Sr, Ti, W, and Zn content in the mammary gland of women aged 16–60 years was investigated. For this purpose, a method based on inductively coupled plasma mass spectrometry (ICP-MS) was employed, which makes it possible to determine the mass fractions of these trace elements in microsamples (mass from 10 mg) of breast tissue. With the help of this method, the material obtained during the autopsy of 38 practically healthy women aged 16–60 years who died suddenly was studied. Trace element mass fractions were determined in two age groups of women: 16–40 and 41–60 years old. Using the parametric Student's t-test and the non-parametric Wilcoxon-Mann-Whitney U-test to compare two age groups, as well as Pearson's correlation coefficients between age and trace elements mass fractions, it was found that the Cu, Mg, Rb, and Zn mass fractions in normal breast tissue decrease with age, while the As mass fraction increase. The phenomenon of the age-related changes of trace elements mass fractions in the normal mammary gland, discovered for the first time, requires further detailed study.