Lithuanian Social Democratic Union (Lithuanian: Lietuvos socialdemokratų sąjunga) was a minor social democratic political party in Lithuania.

The party had 6 representatives at the municipal level by 2011[2] and had no seats in either Seimas or EP.

The leader of the party was Arvydas Akstinavičius.

In 2012 it participated in the Parliamentarian election having formed joint alliance with 2 euroskeptic nationalist parties, named "For Lithuania in Lithuania".

[3] The controversial symbol of this electoral union was a white sheep kicking a black sheep out of the logo [de].