Essential oils obtained by hydrodistillation were analyzed both by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The main constituents found in Achillea oil were as follows: A. filipendulina Lam.: 43.8% santolina alcohol, 14.5% 1,8-cineole and 12.5% cis-chrysanthenyl acetate; A. magnifica Hiemerl ex Hub.-Mor.: 27.5% linalool, 5.8% spathulenol, 5.5% terpinen-4-ol, 4.7% a-terpineol and 4.7% beta-eudesmol; A. tenuifolia Lam.: 12.4% artemisia ketone, 9.9% p-cymene, 7.1% camphor, 5.9% terpinen-4-ol, 4.7% caryophyllene oxide and 4.5% alpha-pinene. Furthermore, the Achillea essential oils were evaluated for antimalarial and antimicrobial activities. A. magnifica and A. filipendulina oils showed strong antimalarial activity against both chloroquine sensitive D6 (IC50=1.2 and 0.68 mu g/mL) and chloroquine resistant W2 (IC50=1.1 and 0.9 mu g/mL) strains of Plasmodium falciparum without any cytotoxicity to mammalian cells up to IC50=47.6 mu g/mL against Vero cells. whereas A. tenuifolia oil showed no antimalarial activity up to a concentration of 20 mg/mL. All three Achillea oils showed no antibacterial activity against human pathogenic bacteria up to a concentration of 200 mu g/mL. A. tenuifolia and A. magnifica oils demonstrated mild antifungal activity against Cryptococcus neoformans (IC50=45, 20 and 15 mu g/mL, respectively).