The Prix du Moulin de Longchamp is a Group 1 flat horse race in France open to horses aged three years or older.

It is run at Longchamp over a distance of 1,600 metres (about 1 mile), and it is scheduled to take place each year in September.

The event is named after the Moulin de Longchamp, a windmill located within the grounds of the racecourse.

The mill was originally part of an abbey, and its foundation stone was laid by Saint Louis in 1256.

The Prix du Moulin was moved to late September in 1974, and to the first Sunday of that month in 1980.