Occupied territories of Baltic States are those territories of Lithuania, Latvia and Estonia, which were in the mentioned countries in the interwar period, but with the Russian (Soviet) occupation after WW2, they weren't attached to Lithuanian, Latvian and Estonian Soviet socialist republics, and were attached to Russian Federative Soviet Socialist Republic instead, hence making them part of Russia. During the occupation the russifying was extremely intenseive in these territories, done by not allowing people to sign nationality as Lithuanian, Latvian or Estonian in censuses, not opening any schools which would teach these languages. Therefore great number of these territories, even those which had clear majorities of Baltic States' people population, was effectively russified. The territories weren't returned to the Baltic States after they gained independence and now stays part of Russia and Belarus. Various stances exists in Baltic States towards the occupied territories: in Estonia, territories occupied from Estonia are showed in great number of maps as part of Estonia, while Lithuanians more or less admitted the loose of these territories and doesn't claims them anyhow; similar map, shown occupied territories as occupied territories rather than parts of Belarus and Russia, was banned after court ruled that it is fascistic in Lithuania. Russians always promoted the idea that it is fascistic to look back at these occupied territories.

The following territories are occupied:

• East coast of Narva (including town of Jaanilinn , now Ivangorod), Estonian territory occupied by Russia. Eastern coast of Narva river, is not large.
• Petseri region , whole region of Estonia in the interwar period, at the south of Lake Peipsi, includes town of Petseri (renamed Pechory by Russians). Larger than the east coast of Narva.
• Arbene region a medium-sized region of Latvia with Arbene town and surroundings, larger than Petseri region. Occupied by Russia.
• Eastern Vilnius region part of Lithuania in early interwar period (Vilnius region), then occupied by Polish troops; when Russians occupied eastern Poland and Lithuania, only western part of Vilnius region was attached to Lithuania, while whole eastern part, two thirds of the region, were attached to Belarus and other bit ceded to Poland after war. The biggest of occupied territories, includes cities of Gardinas (now Grodno) and Lyda (now Lida)
• Suvalkai region - part of Vilnius region in interwar. Ceded to Poland by Russians after the WW2 ended. Unlike in regions occupied by Russians however, here Lithuanians eventually gained more rights, although were discriminated at first. But even now some towns remains with Lithuanian majority and there are Lithuanian schools.

Note - due to some historical and ethnical reasons, Karaliaučius region (or at least it's eastern part, without city of Karaliaučius /Koenigsberg/Kaliningrad itself) can be considered occupied part of Lithuania too, however, because in the interwar period it wasn't part of Lithuania (despite some diplomatic attempts to achieve it), it isn't included here.