Achillea millefolium L. is commonly found as a ruderal plant in Europe and northern parts of Asia and North America, in the temperate climate zone. Numerous phytochemical studies into this species have shown that it is rich in pharmacologically active compounds. The main groups of chemical compounds present in yarrow consist of terpenes, polyacetylenes, flavonoids, coumarins, pyrrolidine alkaloids (such as stachydrine and betonicine), and tannins. This study presents the results of research into the content of select elements and the total of polyphenolic compounds, including the total of phenolic acids. An attempt has been made to determine the correlation between the presence of polyphenolic compounds and the investigated elements. Spearman’s rank correlation between the total of phenolic acids and polyphenolic compounds and the selected elements show that the content of phenolic acids was mainly related to barium, boron, titanium, and iron, whereas the content of polyphenolic compounds was connected with aluminium, boron, chromium, molybdenum, and iron. This was proven by the value of the correlation coefficient, which was greater than 0.6000. In order to illustrate “the data structure” a cluster analysis was used. The total of phenolic acids turned out to be mostly related to the total of polyphenolic compounds, which make direct and the least distant connection with barium, and only then with other metals. These interactions do not necessarily have to be reflected by the values of the rank correlation coefficients as they are typical for linear correlation, while the studied effects may be correlations of a higher degree.