Dausenau is a municipality in the district of Rhein-Lahn, in Rhineland-Palatinate, in western Germany.
Dausenau was one of the oldest possessions of the counts of Nassau and the arms thus show the lion of Nassau. The village was granted city rights in 1348, but these west later lost again. The seals of Dausenau showed from at least the 15th century until 1568 a seal with the arms and St. Castor as a supporter, he is the patron saint of the local church. In an 18th-century seal only the picture of Lady Justice was shown, not a shield with the lion. The present arms were granted in 1937 and go back to the old seal.