Nyitra County (Hungarian: Nyitra vármegye; German: Neutraer Gespanschaft/Komitat Neutra; Latin: Comitatus Nitriensis; Slovak: Nitriansky komitát / Nitrianska stolica / Nitrianska župa) was an administrative county (comitatus) of the Kingdom of Hungary.

In its final phase, it was a strip of land between the Morava river in the north and the town of Érsekújvár (present-day Nové Zámky) in the south, plus an outlier around the town of Privigye (present-day Prievidza).

A predecessor to Nyitra county may have existed as early as in the 9th century at the time of Great Moravia.

The southern part, including the town Nyitra, was ruled as Uyvar Province between 1663 and 1685 by Ottoman Empire.

After World War I, Nyitra county became part of newly formed Czechoslovakia.