Between 2001 and 2005, in the frame of in situ conservation project, the National Institute of Agrarian Innovation (INIA), together with several governmental and non-governmental organizations, studied traditional seed exchange mechanisms among farmers in the 11 administrative regions comprising 69 communities. The objectives were to identify, describe and document pathways and modalities of seed exchange carried out by farmers who cultivate native crops in these regions. Farmers exchange their seeds mainly during agricultural fairs, patron saint festivities and local markets, but many other seed routes also exist; the frequency of their exchange depends on the situation, for example during catastrophic events, such as droughts, floods or earthquakes. The modalities of exchange range from barter, inheritance, gift, purchase, payment for work, loan to exchange among family members. Through traditional seed exchange, farmers not only acquire seeds, but also knowledge and experiences and establish bonds of friendship between them, which allows them to expand their knowledge by sharing their experiences, e.g. with older farmers. Traditional seed exchange mechanisms are thus an important process for sustaining in situ conservation of agrobiodiversity; it is important to conserve these processes along with the agroecosystems where native crops thrive.