Xanthi (Greek: Περιφερειακή ενότητα Ξάνθης) is one of the regional units of Greece. It is part of the Region of East Macedonia and Thrace. The capital is Xanthi. Together with the regional units Rhodope and Evros, it forms the geographical region of Western Thrace.
Xanthi borders the Bulgarian provinces of Smolyan and Kardzhali to the north, and the Aegean Sea to the south. The regional unit of Kavala lies to the west, Drama to the northwest and Rhodope to the east. The Rhodope Mountains cover the northern part of the regional unit. The highest point is Koula, at 1,827m.
The coastal area has a predominantly Mediterranean climate, whereas the northern mountainous part has a colder continental climate.