Lithraea molleoides (Vell.) Engler (Anacardiaceae family) is an evergreen tree species native from South America, considered as a medicinal and edible plant in Argentina [1]. The infusions and decoctions from the vegetative aerial parts are frequently used as medicines for respiratory and digestive illnesses [1]. Besides, the fruits are employed to elaborate fermented beverages [1]. However, in Uruguay this plant is not recognized as medicinal/edible, and it is considered highly allergenic, with frequently reported cases of contact dermatitis in the face and the arms occurring in sensibilized people [2]. Not volatile alk(en)yl-catechols (ACs) have been pointed out as responsible of such contact dermatitis [2]. Moreover, an orally transmitted tradition in Uruguay indicates that such affections are also possible when the people just approach to the trees, without being necessary the contact (that is, an eventual airborne allergy). This suggests the intervention of volatile allergens in the process, a fact that needs to be better investigated given the medicinal/edible utilization of this plant species. As a first step to validate such traditional information, the aim of this work was to characterize the chemical compositions of L. molleoides essential oils (LMEO) of Uruguayan origin using different GC-MS methods and stationary phases. REFERENCES [1] López P., Basile P., Wallace F., Olivaro C., Minteguiaga M., Ferreira F, (2021). Medicinal and Aromatic Plants from South America V.2, Springer Nature, Cham. pp. 339-356. [2] Alé S., Ferreira F., González G., Epstein W., (1997). Allergic contact dermatitis caused by Lithraea molleoides and Lithraea brasiliensis: identification and characterization of the responsible allergens, Am. J. Contact Derm., 8, 144-149.