Achillea millefolium L. is a medicinal herb with more than 100 antifungal and antimicrobial active biological compounds. In the present study, A. millefolium plants at the flowering stage were treated with different concentrations of methyl jasmonate and silver nanoparticles. Treatments increased lipid peroxidation, flavonoid content, and yield of essential oils (ca. 230 %), but reduced radical scavenging capacity and anthocyanin contents of the plants. Cytotoxicity of the extracts of treated plants against cancer HeLa cells was improved as well. Production of certain antimicrobial isoprenoids, i.e., camphor was significantly increased. Certain precious compounds such as allo-ocimene, germacrene, trans-caryophyllene, and farnesol with antibacterial, antifungal, anti-inflammatory, and anticancer effects were also induced just after elicitation of the plants with silver nanoparticles and methyl jasmonate. The results suggested silver nanoparticles as a novel elicitor in plant biotechnology as effective as methyl jasmonate in order for production of desired secondary metabolites in A. millefolium.