Steinburg is a Kreis (district) in the southwestern part of Schleswig-Holstein, Germany. It is situated at the northern bank of the Elbe river, close to its mouth. Area 1056 km², population 132,400 (2002). The district's capital is Itzehoe.
The countryside is very plain. The Stör river, a right-hand tributary of the Elbe, flows through the district. Today the towns in Steinburg gradually become a part of the metropolitan area of the growing city of Hamburg.
Towns in Steinburg: Itzehoe, Glückstadt, Wilster, Kellinghusen.