ABSTRACT In order to contribute to the characterization of oregano implanted in Quebrada de Humahuaca (Jujuy, Argentina) physical properties and chemical composition of essential oils (EO) were determined. Pilot and laboratory scale EO were obtained by steam distillation and hydrodistillation (using a Clevenger type trap) respectively from samples of oregano collected from a small production: Oregano negro(On), Oregano compacto(Oc), Oregano mendocino(Oxm) y Oregano criollo(Oxa). Influence of storing period and extraction techniques were also evaluated. All EO were dextrorotatory (+5 to +15) with 0.92 mean specific gravity and 1.483 mean refractive index. Both hybrids (Oxm and Oxa) and Oc belong to A group characterized by Skoula et al. (1999) because the major compounds are aromatic monoterpenes and/or their precursors. O. Negro is closely related to less common sesquiterpene type. It is necessary a complete work on botanical identity correlated with the physical and chemical characterization of essential oils from different Origanum species grown in our country to have a contrasting quality tool