Illizi (Arabic: ولاية اليزي) is a large province (wilaya) in the south-eastern corner of Algeria named after its eponymous seat.

As of the 2008 census, the province had a population of 52,333 and an annual growth rate of 4.5%.

In January 2013, a hostage crisis occurred in a natural gas facility near In Amenas.

One of the most promising sites for natural gas production is the Ain Tsila gas field in the Isarene permit, some 57% of which is owned by the Irish company Petroceltic International,[5] 18% by the Italian company Enel,[5] and the rest by the Algerian government-owned Sonatrach.

[6] Reportedly, Petroceltic's 56.7% is worth between US$800 million and US$1 billion.