|• Total||1,720 km2 (660 sq mi)|
|• Density||29/km2 (76/sq mi)|
|• Summer (DST)||UTC+3 (EEST)|
|ISO 3166 code||GR-56|
Kastoria (Greek: Περιφερειακή Ενότητα Καστοριάς, Perifereiakí Enótita Kastoriás) is one of the 74 regional units of Greece and is part of the region of Western Macedonia. Its capital is the homonymous city of Kastoria.
Kastoria is situated at the western end of Macedonia in the far north of the country. It borders the regional units of Florina to the north, Kozani to the southeast, Grevena to the south and Ioannina to the southwest. The area of the regional unit roughly corresponds to the ancient Greek region of Orestis of Upper Macedonia. The international border with the Albanian district of Korçë lies on the western edge of the regional unit.
The main mountain ranges are Gramos and Voio in the west (both part of the Pindus range) and Verno in the northeast. The Haliacmon river flows through the area. Lake Orestiada is the largest lake. The regional unit is mountainous with a pronounced continental climate, characterised by cold winters and hot summers.
The regional unit Kastoria is subdivided into 3 municipalities. These are (number as in the map in the infobox):
Kastoria was created as a prefecture (Greek: Νομός Καστοριάς) in 1941. As a part of the 2011 Kallikratis government reform, the regional unit Kastoria was created out of the former prefecture Kastoria. The prefecture had the same territory as the present regional unit. At the same time, the municipalities were reorganised, according to the table below.
|New municipality||Old municipalities||Seat|
|Orestida||Argos Orestiko||Argos Orestiko|