Simultaneous identification of eight phenolic acids (gallic, protocatechuic, chlorogenic, p-hydroxybenzoic, vanillic, caffeic, p-coumaric and ferulic) and three flavonoid aglycones (Iuteolin, kaempferol and apigenin) in Et20-fractions of inflorescences and leaves of five species of Cirsium genus - C. arvense, C. oleraceum, C. palustre, C. rivulare and C. vulgare was carried out by HPLC method. Phenolic acids and flavonoids were analyzed also in terms of quantity. The contents of phenolic acids, expressed as cafifeic acid, determined by the spectroscopic method with Arnov's reagent, were higher in leaves than in flower heads of all investigated species and amounted from 0.15% in C. vulgare inflorescences to 1.31% in C. palustre leaves. The flavonoid contents, indicated by Christ-Miiller's method ranged from 16 mg • 100g1 per dry source in C. arvense and C. palustre inflorescences to 70 mg • 100g ' in C. oleroceum Leaves.