Tsilninsky District (Russian: Ци́льнинский райо́н) is an administrative[1] and municipal[4] district (raion), one of the twenty-one in Ulyanovsk Oblast, Russia.

It is located in the north of the oblast.

The area of the district is 1,293 square kilometers (499 sq mi).

[citation needed] Its administrative center is the rural locality (a selo) of Bolshoye Nagatkino.

[7] The population of Bolshoye Nagatkino accounts for 19.8% of the district's total population.