Altagène is located some 20 km north-east of Propriano and some 25 km north-west of Porto-Vecchio in a direct line. Access to the commune is by road D49 running north from Sainte-Lucie-de-Tallano and ending in the village. The D320 also runs north from Sainte-Lucie-de-Tallano through the western part of the commune and continues to Zoza as road D20. There are some small mountain roads through the commune which is steeply sloped and heavily forested.
There are no identifiable rivers or streams nor other hamlets in the commune.
In 2009, the commune had 52 inhabitants. The evolution of the number of inhabitants is known through the population censuses conducted in the town since 1793. From the 21st century, a census of municipalities with fewer than 10,000 inhabitants is held every five years, unlike larger towns that have a sample survey every year.[Note 1][Note 2]
^At the beginning of the 21st century, the methods of identification have been modified by law No. 2002-276 of 27 February 2002 , the so-called "law of local democracy" and in particular Title V "census operations" which allow, after a transitional period running from 2004 to 2008, the annual publication of the legal population of the different French administrative districts. For municipalities with a population greater than 10,000 inhabitants, a sample survey is conducted annually, the entire territory of these municipalities is taken into account at the end of the period of five years. The first "legal population" after 1999 under this new law came into force in 1 January 2009 and was based on the census of 2006.
^In the census table and the graph, by convention in Wikipedia, and to allow a fair comparison between five yearly censuses, the principle has been retained for subsequent legal populations since 1999 displayed in the census table and the graph that shows populations for the years 2006, 2011, 2016, etc.. , as well as the latest legal population published by INSEE