The Maelbeek (French, pronounced [malbek, -bɛk] ⓘ; former Dutch spelling) or Maalbeek (modern Dutch, pronounced [ˈmaːlbeːk]) is a stream that flows through several municipalities in Brussels, Belgium, including Etterbeek, Ixelles, Saint-Josse-ten-Noode, Schaerbeek.

It is a tributary of the Senne, which it joins up in Schaerbeek, from its source located to the south near La Cambre Abbey.

Maelbeek/Maalbeek metro station is located in the central area of this Maalbeek valley.

There is another stream in the vicinity named Maalbeek,[1] also a tributary to the Senne, in Grimbergen, and two other streams named Molenbeek, found in Beersel and in Laeken.

The Woluwe river also has a tributary named the Kleine (little) Maalbeek, in Kraainem.