Ostprignitz-Ruppin is a Kreis (district) in the northwestern part of Brandenburg, Germany.

Many rivers and lakes can be found in its western, its central and its northeastern part.

The district has always been distinguishable from the West Prignitz, having been settled originally by Slavs from a different part of Mecklenburg.

The eagle in the top of the coat of arms derives from the Counts of Arnstein, who ruled Ruppin in the 13th century.

To the left is a fleur-de-lis representing the Counts von Plotho, a Wendish family who ruled Kyritz, where they had migrated from the Magdeburg area bringing German families such as the von Blumenthals with them.