Nitra District is a district in the Nitra Region of western Slovakia. It is the second most populated of Slovakia's 79 districts, after Prešov District. Before 1996 the present-day district belonged to the West-Slovak region. It is named after the city of Nitra, its main economy and cultural center.

Nitra is a city in western Slovakia, situated at the foot of Zobor Mountain in the valley of the river Nitra. It is located 95 km east of Bratislava. With a population of about 78,353, it is the fifth largest city in Slovakia. Nitra is also one of the oldest cities in Slovakia; it was the political center of the Principality of Nitra. Today, it is a seat of a kraj, and an okres.