Sankt Margarethen (English: Saint Margaret) is a municipality in the district of Steinburg, in Schleswig-Holstein, Germany.

Sankt Margarethen is situated on the lower course of the Elbe River, eight kilometers east of Brunsbüttel and the mouth of the Kiel Canal.

The village was previously known as "Elredefleth", but due to the threat posed by the Elbe river, it was demolished and relocated to its current location.

The resistance of the inhabitants against the destructive forces of water is comparable to Margaret's fight against the dragon of temptation.

At the same time, the number four signifies the close relationships between St. Margarethen and the neighboring communities of Büttel, Kudensee, and Landscheide.