A study on the vascular flora of the Gennargentu Massif (Central-Eastern Sardinia) is presented. According to our results, the flora consists of 948 taxa: 686 species, 249 sub-species, 10 varieties and 3 hybrids, belonging to 97 families and 427 genera. Three taxa are new findings for the flora of Italy and eight for that of Sardinia. Life form analysis revealed, in particular, dominance of 35.65% hemicryptophytes, 34.6% therophytes, 12.13% geophytes and 11.6% (nano)-phanerophytes. As concerns chorology, the Mediterranean element is largely prevailing (68.14%), mainly represented by circumMedit. (29.1%) and Euro-Medit. (23.07%). Endemics are 14.87% of the whole flora (141 taxa), with a large prevalence of Sardo-Corsican (39.01%) and Sardinian taxa (35.46%), i.e. 74.47% of the total. Due to the high number of taxa (9) of Gennargentu exclusive endemics and the geologic and geomorphologic peculiarities, it is here proposed a biogeographic classification for these territories serving to the identification of an autonomous sector.