Uetersen is a town in the district of Pinneberg, in Schleswig-Holstein, Germany. It is situated approximately 7 km (4.3 mi) south of Elmshorn, and 30 km (19 mi) northwest of Hamburg at the small Pinnau River, close to the Elbe river. Uetersen is home to the Rosarium Uetersen, the oldest and largest rose garden in Northern Germany, created in 1929.