The Weiß is a river of North Rhine-Westphalia, Germany, which is 18.1 kilometers (11.2 mi) in length.

Then it flows through the villages Wilgersdorf, Rudersdorf, Anzhausen, Niederdielfen, Kaan-Marienborn, and the city Siegen.

The source of the Weiß, is located within North Rhine-Westphalia, about 220 m north-west of the border with Hesse.

After subsequent passing of the commercial area Klabach-Mühlengraben and southern passage of Flammersbach, it runs past Niederdielfen.

After a short underground section the river Weiß flows into the Sieg in the lower part of Siegen.