The Žeimena River is a river in Aukštaitija, eastern Lithuania, and right tributary of Neris River. Žeimena begins in Labanoras Forest and at Lake Žeimenys. Žeimena flows to the south passing Kaltanėnai town, Švenčionėliai city, and Pabradė city. Its confluence with Neris is located near the border of Švenčionys and Vilnius districts.