The aerial parts of three endemic Centaurea L. species, namely C. tomorosii Micevski, C. soskae Hayek and C. galicicae Micevski, afforded the sesquiterpene lactone cnicin (1) and seven flavonoids: apigenin (2), isokaempferide (3), hispidulin (4), eupatorin (5), cirsimaritin (6), santoflavone (7) and salvigenin (8). The structures of the isolated compounds were determined by UV, 1 H-NMR and 13 C-NMR spectroscopy and HR-ESI-MS spectrometry. 1 H--NMR spectroscopy was used as a method for the quantitative analysis of cnicin.