Srem (Serbian: Срем, Croatian: Srijem, Latin: Sirmium) is a fertile region mostly in northern Serbia and Montenegro in what is known as the Vojvodina. The western parts of Srem/Srijem are in easternmost Croatia, but the border between the region and Slavonia to the west is unclear, and runs somewhere along the line Vukovar-Vinkovci-Županja.
Major cities include Sremska Mitrovica, Zemun, Šid.