Aloysia citriodora accessions from cultivated material, botanical collections, and wild populations were studied by means of their biomass and essential oil production and composition to assist the selection of the most promising genotype. The study was carried out through both field experiments during two year's time and laboratory processes. Data were evaluated by means of univariate and multivariate techniques. Aloysia citriodora intraspecific variation was accounted for by differences in both yield and chemical profiles of the essential oils, but no differences were found in the biomass production. Three chemotypes were identified according to qualitative and quantitative differences of the essential oils. For the higher contents of neral and geranial, Mendoza accession was the most promising to be encouraged for future crops.