Oreini (Greek: Ορεινή meaning "mountainous", before 1928: Μποστενίτσα - Bostenitsa[2]) is a mountain village and a community in the municipal unit of Lampeia, Elis, Olympia, Greece.

Oreini is built on the slopes of Mount Lampeia, part of the Erymanthos range.

Oreini is located 4 km east of Lampeia, 4 km west of Psofida, 6 km south of Agrampela and 32 km northeast of Olympia.

The former name of the village, Bostenitsa, suggests a Slavic origin.

The revolutionary leader Theodoros Papasimakopoulos, who fought in the Greek War of Independence, was from Bostenitsa.