Mikro Dereio (Greek: Μικρό Δέρειο) is a village and a community in the central part of the Evros regional unit in Greece.

It is situated on the left bank of the river Erythropotamos, in the Eastern Rhodope Mountains.

In 2021 its population was 1,836 for the community, which consists of the villages Mikro Dereio, Geriko, Goniko, Mega Dereio, Petrolofos, Roussa and Sidirochori.

The village was founded by the Ottoman Turks in the 14th century, it was known as Malak Dervent (Малък Дервент) in Bulgarian.

According to professor Lyubomir Miletich, the 1912 population was around 200 Bulgarian families.