The Oldmasters Museum is an art museum in the Royal Quarter of Brussels, Belgium, dedicated to European painters from the 15th to the 18th centuries. It is one of the constituent museums of the Royal Museums of Fine Arts of Belgium.

The Royal Museums of Fine Arts of Belgium are a group of art museums in Brussels, Belgium. They include six museums: the Oldmasters Museum, the Magritte Museum, the Fin-de-Siècle Museum, the Modern Museum, the Antoine Wiertz Museum and the Constantin Meunier Museum.