The commune of Sint-Pieters-Leeuw, population 30,000, is located immediately southwest of Brussels. The E19 roadway brushes its eastern edge.
Oudenaken, Ruisbroek (Vlaams-Brabant), Sint-Laureins-Berchem, and Vlezenbeek are boroughs within the municipal district of Sint-Pieters-Leeuw. (There is another Ruisbroek in Willebroek, Antwerpen province.)