The Belarus–Lithuania border is an international border almost 679 km in length between Belarus and Lithuania and also serves as an outer border of the European Union and the Schengen area. The border is defined by the treaty of February 6, 1995 between the two countries. Ground demarcation of the border was complete in 2007.
380 km of the border is on land, while 299 are on water, crossing lakes, e.g. Lake Drūkšiai and following some rivers, e.g. Dysna River and Neman River. The border is based on the border between Lithuanian SSR and Belarusian SSR within Soviet Union, which had remained largely stable since 1940.
Since 2004 the border has served as the outer border of the European Union and, since 2007, the Schengen area. These developments brought increased border controls and stricter visa requirements for crossing between the two countries, although an agreement signed in 2010 aims to implement simplified traveling for people living within 50 kilometers of the border. As an outer border of EU, the border with Belarus has seen the most illegal attempts to cross the border in Lithuania, with 246 attempts in 2010.
The treaty defines the border as starting at the border tripoint of Lithuania, Latvia and Belarus, where there is a monument (55°40′50″N 26°37′48″E / 55.68056°N 26.63000°E). It goes southeast across Lake Drūkšiai, following river Apyvardė, across lakes Apvardai and Prūtas, further following Dysna River to the east, and further to Adutiškis railway station. It further goes north of Belarusian settlement Lentupis, east of the Lithuanian settlement Šumskas, across the road Vilnius - Maladzyechna, goes around the area of Lithuanian settlement Dieveniškės from the east, south and west, goes to the North of Belarusian settlement Benekainys, crosses the road Vilnius-Lida and further follows Šalčia river. It further continues to the south of Lithuanian city Eišiškės, follows Načia river, goes to the south of Lithuanian settlement Dubičiai, reaches the source of Kotra River and further follows this river, then across lakes Grūda ir Dubas. It further crosses the railroad Vilnius-Grodno next to the stop Senovė, and the railroad to Druskininkai to the north of the stop Pariečė, continuing west towards Neman river and up against the current, and further following Mara river to the border tripoint of Belarus, Lithuania and Poland (53°57′22″N 23°30′54″E / 53.95611°N 23.51500°E).