Lauenburg is a Kreis (district) in the southeastern part of Schleswig-Holstein, Germany. It is situated at the northern bank of the Elbe river. Area 1263 km², population 170,000 (2002). The district's capital is Ratzeburg.
This area contains a number of historically important towns, e.g. Lauenburg, Mölln and Ratzeburg. This importance was due to the Old Salt Route (Alte Salzstraße), one of the major medieval trade routes. Salt from the salt-works south of the Elbe river was transported northward to Lübeck. The transport of salt was also the motive for constructing the oldest artificial waterway of Europe, the Stecknitz Canal (1398). It was replaced in 1900 by the Elbe-Luebeck Canal.
The landscape is characterized by numerous lakes, forming the Lauenburg Lakes Nature Park. The largest lake is the Ratzeburger See with an area of 16 km².
The district of Lauenburg is sometimes called the "duchy of Lauenburg", since it was a duchy from 1260 to 1689. The town of Lauenburg was the capital of this medieval fief, but today Ratzeburg is more important.
Towns in the district of Lauenburg: Ratzeburg, Lauenburg, Mölln, Geesthacht, Schwarzenbek.