The objective of this investigation was to characterize the antimicrobial activity of the natural preservative, intended for cosmetic purpose, Kopraphinol (INCI name: Lactobacillus/Radish Root Ferment Extract Filtrate). It was tested against a panel of selected bacteria and mycetes by using conventional microbiological techniques (determination of MIC, time killing assay), and a chal-lenge test was used to verify its potential preservative in an O/W cream. Kopraphinol has shown an interesting antimicrobial effectiveness comparable to methylparaben. Moreover, it fulfilled challenge test criterion A and has proven effective against microbial contamination. The results obtained show that Kopraphinol can be considered a promising and effective candidate for anti-microbial preservation of cosmetics and could successfully complement or even replace conven-tional preservatives.