Trnje is a district in the City of Zagreb, Croatia. According to the 2011 census, the district had 42,282 residents. It is located in the central part of the city, south of Donji grad across the railway , east of Trešnjevka , west of Peščenica , and north of the river Sava. The Slavonska Avenue intersects Trnje.
Trnje was amalgamated into the city in 1927 by Mayor Vjekoslav Heinzel, along with several other new districts, mainly for the purpose of housing people needed for Zagreb's industrial sector expansion.