Virolahti (Swedish: Vederlax) is the southeastern-most municipality of Finland on the border of the Russian Federation. It is located in the province of Southern Finland and is part of the Kymenlaakso region. The municipality has a population of 3,488 (31 January 2012) and covers an area of 558.92 square kilometres (215.80 sq mi) of which 186.97 km² (72.19 sq mi) is water. The population density is 9.38 inhabitants per square kilometre (24.3 /sq mi).

The municipality is unilingually Finnish.

Before the World War I the Russian Emperor Nicholas II used to spend summers with his family in the archipelago of Virolahti with his yacht Standart.

The Vaalimaa border crossing, which connects the municipality with Russia, is located in Virolahti.

Virolahti lost some of its area (over 100 km²) to Soviet Union in Paris Peace Treaties, 1947 after World War II.

Villages marked with an asterisk (*) are now completely or partially on the Russian side:

Alapihlaja, Alaurpala*, Eerikkälä, Hailila, Hanski, Hellä (Heligby), Hämeenkylä (Tavastby), Häppilä, Järvenkylä, Kattilainen, Kiiskilahti*, Kirkonkylä, Klamila, Koivuniemi, Koskela*, Koskelanjoki, Kotola, Kurkela, Laitsalmi*, Länsikylä (Flonckarböle), Martinsaari*, Mattila, Mustamaa, Nopala, Orslahti*, Paatio* (Båtö), Pajulahti, Pajusaari*, Pitkäpaasi*, Pyterlahti, Ravijoki, Ravijärvi, Reinikkala, Rännänen (Grennäs), Sydänkylä (Kallfjärd), Säkäjärvi, Tiilikkala, Vaalimaa (Vaderma), Vilkkilä, Virojoki, Yläpihlaja, Yläurpala* (now Torfjanovka).