The Molenbeek-Ter Erpenbeek or in popular language Molenbeek (English: Millbrook-Ter Erpenbrook) is a brook in the Denderstreek region of Belgium.

This brook is not to be confused with a 22-km water body called Molenbeek, which also flows through Erpe-Mere (and Herzele).

The 22-km Molenbeek is part of the Drie Molenbeken drainage basin.

The basin of the Molenbeek is located in the province of East Flanders and flows through the municipalities of Zottegem (Godveerdegem, Erwetegem, and Grotenberge), Herzele (Herzele, Sint-Lievens-Esse, Woubrechtegem, and Ressegem), Haaltert (Heldergem, Kerksken, and Haaltert), Erpe-Mere (Aaigem, Mere, and Erpe) and Aalst (Aalst and Hofstade).

From its source in Godveerdegem to the delta in Hofstade, the Molenbeek has the following tributaries: Plankebeek, Meilegembeek, De Burg's Heerendijkbeek, Grep, Holbeek, Steenbeek, and Zijpbeek.