In this work, the volatile oils from the plants of Apium graveolens L., Voacanga africana Staph. and Allium cepa L. were analysed for their constituents by GC-MS. Limonene (40.5%), β-selinene (16.3%), cis-ocimene (12.5%) and β-caryophyllene (10.5%) were the main compounds of A. graveolens, while V. africana was predominantly comprised of precocene I (7-Methoxy-2,2dimethylchromene) (95.2)%. On the other hand, the volatile oil of A. cepa was characterized by sulphur compounds, of which diallyl trisulphide (58.8%), methyl allyl trisulphide (18.5%) and diallyl disulphide (17.7%) were in abundance.