Djelfa is the capital city of Djelfa province, Algeria. It has a population of 154,265 (1998 census).

A pleasant medium-size city, north-central Algeria, in the Ouled Nail Mountains at an elevation of 3,734 feet (1,138 m). It is situated between the towns of Bou Sa�da and Laghouat. Djelfa town is at a point of transition between the dry, steppelike High Plateaus of the north, with their chotts (intermittent salt lakes), and the Sahara (south). The town was founded in 1852 as a French military post on a geometric plan. It serves as an important livestock market centre for the seminomadic Ouled Nail confederation. Djelfa is on the 12,000 mile Africa Trail.