Quartu Sant'Elena (Cuartu Sant'Alèni o Quartu Sant'Aleni in Sardinian) is an Italian municipality of 68,326 inhabitants in the metropolitan city of Cagliari in Sardinia. It is the third municipality in the region by population, after Cagliari and Sassari.

The city of Quartu Sant'Elena is located on the southern part of the Campidano plain. On the eastern side of the city, however, is the mountain massif of the Sette Fratelli, covered with woods, from whose trees cork is obtained, and is a natural habitat for deer, golden eagles and wild boars. The highest peak is Mount Serpeddì, which reaches 1,069 meters in height.