Southern ecology 24: 203-211 (2014) Reintroduction of wild species is a recommended tool when it favours ecosystem functionality. It is a long-term process during which the various ecological aspects involved in the reintroduction process need to be assessed. In the case of large wild herbivores, an important aspect is to know forage habits. This study identified the species-level diet of the Guanacos population (Lama guanicoe) reintroduced into the Quebrada National Park of the Condorito (Córdoba, Argentina). To this end, samples of fresh faeces were collected from February to August 2009 in the territory occupied by the breeding groups within the Park. The botanical composition of the samples was determined by microhistological analysis. The diet of the reintroduced guanacs consisted mainly of low-carrying grasses and cyperaceae, characteristic of the waves, and despite the high diversity of vascular plants present in the study area, only five species accounted for between 71 % (for cold and dry months) and 93 % (for warm and wet months) of the diet consumed during the study period: Sorghastrum pellitum, Chascolytrum subaristatum, Carex fuscula, Eleocharis pseudoalbibracteata and Lachemilla pinnata. In addition, the first four species were consumed in a significantly higher proportion than the abundance in the field, indicating that the re-introduced guanacs behaved as selective consumers. On the other hand, there was a small seasonal variation consisting of the consumption of plant species, with the consumption of high-abundant grasses D. Hieronymi and P. stuckertii, dominant in the Pajonales, and woody species, increasing in the cold and dry months. This is likely to be due to lower productivity during cold and dry months in the study area.