The Lachte is a 38-kilometre-long (24 mi) right-hand tributary of the Aller in the Südheide Nature Park in the north German state of Lower Saxony.

It initially flows southwest, feeds at 5 km (3.1 mi) long row of fish ponds near the Auermühle Estate (Gut Auermühle) and is then joined from the left by the Kainbach stream and, beyond the town of Steinhorst (which has a water wheel in its coat of arms), the Jafelbach.

Near Lachendorf the river swings west and discharges into the Aller near Lachtehausen [de] (part of Altenhagen), a village within Celle district.

In 1997 the "Upper Lachte, Kainbach, Jafelbach" Nature Reserve was opened with an area of 1,090 hectares (2,700 acres).

[3] Although only following the western section of the river, the narrow gauge line from Celle to Wittingen was known as the Lachte Valley Railway.