Argireline, a peptide with the sequence: Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2, also known as Acetyl Hexapeptide-8, reduces facial lines and wrinkles by destabilization of the formation of the SNARE complex (SNAP Receptor, soluble N-ethylmaleimide sensitive factor (NSF) attachment protein receptor), thus preventing muscle contraction. It is a biosafe cosmetic alternative to the botulinum toxin. The method of choice in bioactive peptide analysis is reversed-phase high performance liquid chromatography coupled with mass spectrometry (LC-MS). The aim of this work as to present the properties of Argireline and the analysis of cosmetic products containing this peptide. Previous reports on possible Argireline transformations in cosmetic formulations have not confirmed deacetylation, whereas the oxidation of methionine residue was detected by our team. As the biological activity of the oxidized Argireline is not known, further biological studies, as well as efficient analytical procedures for transformation monitoring and quality control in cosmetic products, are necessary.