The Nature Reserve “Isla Martin Garcia” is located within the environment of the top of the Río de la Plata and near the southern boundary of the Río Parana Delta. The island with an area of 168 ha belongs to the phytogeographic region of Paranaense Forests. Many authors have described the vegetation, but most of the lichen biota was unknown, since there was no formal list for it. The sampling was opportunistic, epiphytic lichens on trunks and branches were collected, finding a total of 50 species. Of these, 37 were cited for the province of Buenos Aires while 8 are new records for the province of Buenos Aires and 5 are new records for Argentina. All are species found in the tropical and subtropical areas of Argentina and South America, a distribution coincident with the observations by other authors for vascular plants.