¹Department of Pharmacognosy, Faculty of Pharmacy, Ankara University, 06100 Ankara, Turkey DOI : 10.12991/jrp.2019.164 Medicinal plants used in traditional medicine have been increasingly noticed within recent years in pharmaceutical, cosmetic and nutraceutical industry. Herein, methanolic extracts of Achillea biebersteinii Afan., A. setacea Waldst. Et Kit. and A. wilhelmsii C. Koch were investigated for their total phenolic content and antioxidant activity with the main focus on phenolics. The total phenolic content varied widely in different parts of the three tested Achillea species, ranging from 113.2±1.9 to 178.4±9.5 mg GAE/g extract using Folin Ciocalteu method. DPPH and ABTS antioxidant activity tests were used to evaluate and compare the antioxidant activity of the species. Both the DPPH and ABTS assay results revealed that the radical scavenging activity of A. biebersteinii leaf extract is remarkably high with IC50 values of 0.377±0.011 and 0.016±0.002 mg/mL, respectively. Furthermore, a newly validated RP-HPLC-DAD method was developed and used to determine the phenolic compound profile of the methanol extracts. Phenolic components, such as gallic acid, chlorogenic acid, caffeic acid, ferulic acid, p-coumaric acid, rutin, quercetin, luteolin, apigenin and kaempferol were analyzed by HPLC-DAD. The significant antioxidant properties of the extracts could be attributed to the phenolics of the Achillea species. Keywords : ABTS; Achillea; DPPH; HPLC-DAD; phenolic compounds