The presented study revealed that there were changes in the phenolic compounds profi le of extract of wild thyme (Thymus serpyllum L.) after γ-irradiation at the dose of 5 kGy. Ethanolic extracts of irradiated and non-irradiated herb were prepared and their compounds were analyzed by RP--HPLC-DAD technique. Between thirty two detected constituents, twelve phenolic compounds classifi ed as hydroxybenzoic and hydroxycinnamic acids derivatives, fl avones and fl avanones were identifi ed. Among them, caffeic acid derivatives and fl avones predominated with the highest content of rosmarinic acid and luteolin-7-O-glucoside, respectively. Additionally, thymol was recognized in the analyzed extracts. γ-Irradiation slightly affected the quantitative profi le of phenolic compounds of a wild thyme ethanolic extract. Only four constituents differed signifi cantly (P<0.05) in terms of their content in the irradiated and non-irradiated samples. The content of phenolic acids (p-coumaric and caffeic acids) decreased and that of fl avonoid aglycons (luteolin and eriodictyol) increased after the γ-ray treatment.