the essential oil of the flowers of tridax procumbens l. was obtained by hydro-distillation and analyzed by gas chromatography equipped with a flame ionization detector (gc-fid) and gas chromatography coupled with mass spectrometry (gc/ms). twenty-six compounds were identified, which comprised 90.6% of the total constituents. the most abundant compound was ( z)-falcarinol (25.9%), followed by -selinene (15.3%), limonene (8.3%) and zerumbone (4.3%). antimicrobial activity was tested against six gram-positive and eight gram-negative bacteria, and three fungi. the oil was active against the tested gram-positive bacteria at a concentration range of 0.14 +/- 0.03 - 0.57+/-0.05 mg/ml, while 0.67 +/- 0.12 - 4.58 +/- 0.41 mg/ml was effective against the studied gram-negative bacteria. remarkable antifungal activity was found against the tested fungi at a concentration range of 0.06 +/- 0.008 - 0.10 +/- 0.01 mg/ml.