Bad Marienberg is a town in the Westerwaldkreis area of the state of Rhineland-Palatinate, Germany. The town is located in the Westerwald mountains between Limburg an der Lahn and Siegen. Past it, from east to west, flows the river Nister. Three villages belongs to the district of Bad Marienberg, named Eichenstruth, Langenbach und Zinhain. Bad Marienberg was the capital of the Oberwesterwaldkreis from 1866 to 1939.