Rethymno Prefecture (Greek: Νομός Ρεθύμνου or Νομός Ρεθύμνης) is a prefecture in the island of Crete. Rethymno is one of the four prefectures of Crete. It is situated between the prefectures of Chania and Heraklion, abutting the Cretan Sea in the north and the Libyan Sea in the south.
Its capital, which has the same name as the prefecture, is situated 58 km from the town of Chania and 78 km from the town of Heraklion. The central part of the town of Rethymno is built on the cape of the northern shore of the prefecture.Today its main income is tourism. The countryside of the prefecture is also based economically on agriculture and herding. The villages of Anogia Zoniana Livadia, and the rest of Mylopotamos county villages is reported to have the highest fertility rate of the EU. Three other notable towns in the Rethymno prefecture are Plakias, Spili and Agia Galini.

Due to the hot summers and the long periods of rainfall, which lasts from autumn almost to April, the climate can be characterised as "temperate Mediterranean". Temperatures range around 14 C in winter and 29 C in summer. Furthermore, strong northerly and southerly winds play a significant role in this area with respect to meteorological phenomena.