Bäk District (Pashto: باک ولسوالۍ, Persian: ولسوالی باک) is situated in the northern part of Khost Province, Afghanistan. It borders Sabari District to the west, Paktia Province and Jaji Maydan District to the north, Pakistan to the east and Tere Zayi District to the south. The population was 19,600 in 2006. The district center is the village of Bäk, located in the southern part close to the border with Tere Zayi District.