The Vilnia is a river in Belarus and Lithuania. Its source is near the villages of Kiemėnai and Vindžiūnai, 6 km south of Šumskas, nearby to the A3–M7 Medininkai–Kamenny Log border crossing complexes of the Belarus–Lithuania border.
The Vilnia is 79.6 km long and its basin covers 624 sq. km.
For 13 km, its flow marks the Belarus-Lithuania border, and the remaining 69 km are in Lithuania where it flows into the Neris River at Vilnius.
Eventually, its waters, via the Neris draining into the Neman River, reach the Baltic Sea.
