The degree of variability in the composition of herbal medicines was studied on the example of the preparation of St. John's wort from various Ukrainian producers. The Cu and Zn contents were the most stable compared to other (Fe, Mn, Co, Cr, Ni, Pb, Cd) microelements among plants of different origins. The content of toxic elements (Pb, Cd) did not exceed the established standards. Meanwhile, a 2-3-fold concentration difference was observed for hyperforin, an active pharmaceutical ingredient in St. John's wort. Thus, the existing standards do not ensure the stability of the composition of herbal preparations. As a result, the quality of medicinal drugs can be significantly different. The key reason for the variation in plant composition is environmental influence, including anthropogenic factors. Existing training programs for prospective specialists of the pharmaceutical industry do not pay enough attention to the impact of the environment on the quality of herbal raw materials. Necessary changes to the syllabi of relevant disciplines are formulated to eliminate this shortcoming and ensure sustainable development of raw materials sources for the pharmaceutical industry.