The Stuttgart Open (sponsored since 2022 by Hugo Boss and called BOSS Open) is an ATP Tour 250 series professional tennis tournament on the ATP Tour. Between 1970 and 1989, the Stuttgart Open was a Grand Prix tennis circuit event. From 1990 to 1999, the Stuttgart Open was an ATP Championship Series tournament. The Championship Series name was changed to ATP International Series Gold in 2000, and the Stuttgart Open was a part of this series from 2000–2001 and 2003–2008. In 2002, the Stuttgart Open was briefly demoted for one year to ATP International Series status, which was renamed to the ATP Tour 250 in 2009, and it has retained the classification ever since.