Rethymno (Greek: Περιφερειακή ενότητα Ρεθύμνου) is one of the four regional units of Crete, Greece. Its capital is the city of Rethymno. Today its main income is tourism. The countryside is also based economically on agriculture and herding.

The regional unit Rethymno is subdivided into five municipalities. These are (number as in the map in the infobox):

• Agios Vasileios (2)
• Amari (3)
• Anogeia (4)
• Mylopotamos (5)
• Rethymno (1)

The Rethymno prefecture (Greek: Νομός Ρεθύμνου or Ρεθύμνης) was created while Crete was still an autonomous state, and was preserved after the island joined Greece in 1913. As a part of the 2011 Kallikratis government reform, the Rethymno regional unit was created out of the former prefecture. 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
Agios Vasileios	Lampi	Spili
	Foinikas
Amari	Kourites	Agia Foteini
	Sivritos
Anogeia	Anogeia	Anogeia
Mylopotamos	Geropotamos	Perama
	Kouloukonas
	Zoniana
Rethymno	Rethymno	Rethymno
	Arkadi
	Lappa
	Nikiforos Fokas

• Rethymno Province - Rethymno
• Agios Vasileios Province - Spili
• Amari Province - Amari
• Mylopotamos Province - Perama

Note: Provinces no longer hold any legal status in Greece.

The main towns of the regional unit Rethymno are (ranked by 2021 census population):

• Rethymno 34,085
• Violi Charaki 3,185
• Anogeia 2,201

• Kostas Moundakis
• Nikos Xilouris
• Thanassis Skordalos
• Nick the Greek

• List of settlements in the Rethymno regional unit