The Duewag AG was one of Germany's major manufacturers for rail vehicles. The business was sold in 1999 to Siemens transportation.

The company was founded in 1898 as Waggonfabrik Uerdingen AG in Uerdingen and produced rail vehicles under the brand DÜWAG. After the merger with Düsseldorfer Waggonfabrik in 1935, railway vehicles were built in Uerdingen, while the Düsseldorf plant produced mainly local traffic vehicles, namely tramway and light rail vehicles. In 1981, the company changed its name from Waggonfabrik Uerdingen AG to Duewag AG and began to use the Duewag spelling.

Duewag was sold to Siemens in 1989 by Talbot from 1996 Siemens began to consolidate its rail vehicle production facilities and the division was subsequently absorbed in 2000 now producing Siemens Combino vehicles. In 2002 a new 6000m² entrance/office building was built at the plant. The last tramcar to be manufactured at Uerdingen was in 2012 with production of the new Avenio model moving to Vienna however commuter and high speed vehicle production remains at the plant.

Duewag vehicles were close to a monopoly market in West Germany, as nearly every tram and light rail vehicle purchased from the 1960s onward was built by DÜWAG.