Gruuthuse, Medieval castle estate in Oostkamp, Belgium.

Gruuthuse is a medieval castle estate in Flanders with a triangular layout, multiple towers, and a broad moat encircling the main building. The property spans 41 hectares (about 101 acres) of private grounds surrounded by woodlands and landscaped areas.

Galbert of Bruges first mentioned the castle of Oostkamp in 1128, when William Clito besieged it because its lord backed Diederik of Alsace. In 1454 Lodewijk van Brugge, lord of Gruuthuse, bought the lordship; Edward IV of England stayed there in 1470. François d'Ursel demolished much of the medieval castle at the end of the 17th century, and in 1887 Charles-Marie d'Ursel had the present building erected to René Buyck's design, completed in 1890 and occupied in 1892.

The estate takes its name from the Gruuthuse family, who acquired the lordship of Oostkamp in 1454 through Lodewijk van Brugge. The castle is not open to the public, so the 1890 neo-Flemish design by René Buyck is seen from outside; the grounds are private.

The estate now operates as an event venue with multiple rooms available for meetings, conferences, and workshops accommodating roughly 8 to 80 people. Since it sits on private grounds, visitors should check ahead for access information and availability before planning a visit.

The Hippodrome Gruuthuse racecourse opened in 1935 east of the Gruuthuselaan, built by Count Louis d'Ursel. Its concrete grandstand structures, designed by building materials dealer Germain D'Hoore, survive after the track was demolished around 1965 and the site returned to forest and meadow.