Saarlouis (Sarrelouis in French) is a Kreis (district) in the middle of the Saarland, Germany.

Neighboring districts are Merzig-Wadern, Sankt Wendel, Neunkirchen, Saarbrücken, and the French département Moselle.

The territory of the city Saarlouis which was built to protect the border, came to France as part of the three Bishoprics.

The district showed the fundamental problem of the whole empire: A strong influence of foreign rulers and micro-sized territories.

After the Napoleonic wars the area went to Prussia, which in 1816 created the district as part of its Rhineland province.