abstract the essential oil obtained from aerial parts of baccharis articulata (lam.) pers. from rio grande do sul, southern brazil, was analyzed by gc, gc/ms, and chiral phase gas chromatography (cpgc). twenty-nine compounds representing ca 86.1 % of the oil were identified. the main compounds in the oil were -pinene (39.0%), cis--guaiene (9.8%), -muurolene (5.8%), limonene (4.8%), -pinene (4.5%), -gurjunene (4.4%) and spathulenol (4.2%). the antimicrobial activity of the oil was evaluated against seven microorganisms using the broth microdilution method. the oil displayed antimicrobial activity against gram-positive and gram-negative microorganisms (mic=2.5 mg/ml).