Ioannina (Greek: Περιφερειακή ενότητα Ιωαννίνων) is one of the regional units of Greece. It is part of the Epirus region. Its capital is the city of Ioannina. It is the largest regional unit in Epirus, and one of the largest regional units of Greece.
Ioannina borders Albania in the north, and the regional units of Kastoria in the northeast, Grevena and Trikala in the east, Arta in the southeast, Preveza in the south and Thesprotia in the southwest and west.
Ioannina is a mountainous region, dominated by the Pindus mountains, that cover the eastern part of the regional unit. The main subranges of the Pindus are from north to south: Gramos, Smolikas (2,637 m, the highest of the Pindus), Tymfi, Lygkos, Lakmos and Athamanika. The lower Xerovounio mountains are situated in the south, and the Tomaros in the southwest.
Lake Ioannina is the largest lake of Epirus. Several major rivers have their source in the Ioannina regional unit, including Aoös, Arachthos and Acheron.
The area of the present regional unit of Ioannina joined Greece in 1913, after the First Balkan War.