Osterode is a Kreis (district) in the southeastern part of Lower Saxony, Germany. It comprises the southwestern part of the Harz mountains. Area 636 km², population 85,500 (2000). The capital of the district is Osterode[?].

More than two thirds of the district's area are occupied by the Harz mountains, including the southern portion of the Harz National Park.

Towns in the district: Osterode[?], Herzberg[?], Bad Lauterberg[?], Bad Sachsa[?], Bad Grund[?].