Lennik is a municipality located in the Belgian province of Flemish Brabant. The municipality comprises the towns of Sint-Kwintens-Lennik, Sint-Martens-Lennik, and Gaasbeek. On January 1, 2006, Lennik had a total population of 8,694. The total area is 30.80 km² which gives a population density of 282 inhabitants per km².