The leaf volatile constituents of Minthostachys verticillata from various phytogeographic areas of Argentina were steam distilled and analyzed by GC and GC/MS. The composition of the oil was extremely variable from one population to another, leading to the conclusion that there are several chemotypes in this species. Thymol and carvacrol, which were absent in the oils of another populations previously reported, were the major components (> 10.0%) in the oils of Potrero and Sebastian populations (Catamarca). Pulegone was found in oils from Cordoba, San Luis, Catamarca (Balcosna population) and Tucuman (Potrero de las Tablas population) in high amounts (>21.1%). A high percentage of carvone (35.2%) was found in the oil obtained from Rancho de la Cascada plants.