The aerial parts of the endemic Achillea teretifolia Willd. and A. nobilis L. subsp. neilreichii (Kerner) Formanek collected from Beysehir were investigated for their essential oil compositions and several biological activities. The essential oils were analyzed both by gas chromatography (CC) and gas chromatography-mass spectrometry (GC-MS). The main components were identified as 1,8-cineole (34%), camphor (11%). terpinen-4-ol (8%), and alpha-thujone (5%) for A. teretifolia essential oil, while fragranyl acetate (32%), fragranol (24%), and beta-eudesmol (8%) for A. nobilis subsp. neilreichii essential oil, respectively. The essential oils were also evaluated for their in vitro antimicrobial activity and their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals using microdilution techniques as an index for the evaluation of antioxidant activity. Both essential oils were found to be effective against the tested human pathogenic microorganisms (MIC 0.5 to >2 mg/ml) and DPPH (IC50 > 0.5 mg/ml) assay as compared to the references.