This research is being carried out among two Mbyá-guaraní communities, settled in Kuña Piru valley in the province of Misiones, Argentina. The area of study is located in the so called Paranaense rainforest, which is characterized by its high biodiversity. The ethnic and cultural variability of the population living in Misiones stands out, and is the result of the migratory flow that arrived in our country from Europe, Asia and bordering countries in the late 19th and early 20th centuries. The contact situations in intercultural and interethnic contexts propitiate the exchange of knowledge and practices, which causes adjustments in the relationships between the Mbya and their environment. A wide range of alternatives derives from this situation, regarding both gathering ways and the circulation of plant resources for therapeutic use. In the last years the commercial value of these resources has led to an increase in the demand on the part of herbal establishments that provide medicinal plants to the national market. As a result of that, the gathering of medicinal plants by the Mbya has widened, to include species whose therapeutic uses are not known by the members of these communities. We will present in this paper the wild plants gathered which are meant for commercialization, considering gathering places, ways of use and purposes. We will discuss how a traditional activity –gathering– has become inserted in new contexts and is now regulated by market conditions. byá-guaraní communities, settled in Kuña Piru valley in the province of Misiones, Argentina. The area of study is located in the so called Paranaense rainforest, which is characterized by its high biodiversity. The ethnic and cultural variability of the population living in Misiones stands out, and is the result of the migratory flow that arrived in our country from Europe, Asia and bordering countries in the late 19th and early 20th centuries. The contact situations in intercultural and interethnic contexts propitiate the exchange of knowledge and practices, which causes adjustments in the relationships between the Mbya and their environment. A wide range of alternatives derives from this situation, regarding both gathering ways and the circulation of plant resources for therapeutic use. In the last years the commercial value of these resources has led to an increase in the demand on the part of herbal establishments that provide medicinal plants to the national market. As a result of that, the gathering of medicinal plants by the Mbya has widened, to include species whose therapeutic uses are not known by the members of these communities. We will present in this paper the wild plants gathered which are meant for commercialization, considering gathering places, ways of use and purposes. We will discuss how a traditional activity –gathering– has become inserted in new contexts and is now regulated by market conditions. Key words: Gathering, marketing, medicinal plants, Mbya-Guarani, Northeastern Argentina