The Steinhuder Meerbach is a 34-kilometre-long (21 mi) orographically right-hand tributary of the River Weser in the German federal state of Lower Saxony.

Within the town of Nienburg the Meerbach is also commonly known as the Aue, and in the neighbouring villages to the south also as the Bäke.

Its channel flow significantly exceeds the inflow of above-ground headstreams of the lake.

It leaves the lake at its northwestern end and then flows west through the Meerbruch nature reserve and the village of Rehburg.

At the point where the river bends sharply to the west in Nienburg shortly before its confluence with the Weser the Steinhuder Meerbach used to flow further to the northeast and discharge into the Aller at Rethem.