The chemical composition of essential oil samples of the aerial parts of Lantana canescens, Lantana tilcarensis, Lantana trifolia, Aloysia citriodora, Aloysia gratissima, Aloysia castellanosii and Aloysia catamarcensis from northwest Argentina, phytogeographic areas of Yungas, Puna, Parque Chaqueño and Monte, have been analyzed by GC and GC/MS. The main oil component group present in the oils of the aerial parts of Lantana species were sesquiterpene hydrocarbons (> 24.8%). In contrast, the main compound group found in the oils of Aloysia species were oxygenated monoterpenes (> 19.6%). The comparison with previous studies performed by other authors points to a significant variation in the chemical composition of essential oil depending on the origin of the plants.