The Reich Ministry for the Occupied Eastern Territories (German: Reichsministerium für die besetzten Ostgebiete (RMfdbO) or Ostministerium, pronounced [ˈɔstminɪsˌteːʁiʊm] ⓘ) was created by Adolf Hitler on 17 July 1941 and headed by the Nazi theoretical expert, the Baltic German Alfred Rosenberg.

In February 1942, under Rosenberg's plans, the Ministry tried to promulgate a program of land reform in the occupied territories in the Soviet Union that included promises of decollectivization through the abolition of kolkhozes and the re-distribution of land to peasants for individual farming.

The Wehrmacht never established firm possession of the areas designated for the last two Reichskommissariats and so German civilian control never developed there.

In practice, the appointment of Erich Koch to administer the Reichskommissariat Ukraine substantially undermined Rosenberg's authority.

Furthermore, Rosenberg's ministry was denied authority over army and other security formations within the occupied territories.