The Declaration of Pillnitz was a statement of five sentences issued on 27 August 1791 at Pillnitz Castle near Dresden (Saxony) by Frederick William II of Prussia and the Habsburg Leopold II, Holy Roman Emperor who was Marie Antoinette's brother. It declared the joint support of the Holy Roman Empire and of Prussia for King Louis XVI of France against the French Revolution.

Pillnitz Palace is a restored Baroque schloss at the eastern end of the city of Dresden in the German state of Saxony. It is located on the right bank of the River Elbe in the former village of Pillnitz. It was the summer residence of many electors and kings of Saxony; it is also known for the Declaration of Pillnitz in 1791.