The essential oils from three wild Brazilian plant species from high altitude were obtained by hydrodistillation and analyzed by GC/FID and GC/MS. The most noteworthy volatile compounds from Baccharis parvidentata were sabinene (15.2%), himachalol (10.3%), β-pinene (9.2%) and δ-3-carene (5.7%). The oil from Hyptis monticola was characterized predominantly by trans-caryophyllene (11.3%), (E)-methyl-cinnamate (7.8%), germacrene D (6.9%), limonene (6.6%), α-muurolene (6.4%) and β-pinene (5.6%) whereas the most prevalent components in the oil of Lippia origanoides were (E)-methyl cinnamate (40.0%), hedycaryol (8.0%), α-eudesmol (8.0%) and β-eudesmol (7.0%). Essential oils from B. parvidentata and L. origanoides displayed antibacterial and antifungal activities. Minimal inhibitory concentrations ranged from 78 μg/mL to 2500 μg/mL. Cryptococus neoformans and Trycophyton rubrum were the most sensitive microorganisms. The MIC and the microbicidal concentrations were identical. This is the first report on the chemical composition of Hyptis monticola and Baccharis parvidentata.