The Eine is a river, just under 40 kilometres (25 mi) long in the German state of Saxony-Anhalt, which rises southeast of Harzgerode in the Harz mountains at 420 metres (1,380 ft) above sea level.
The Eine flows north of the B 242 federal road to Friedrichsrode in an easterly direction and then swings northeast into the Harz Foreland. The river channel runs through Alterode, Welbsleben and Westdorf to Aschersleben. The tributaries of the Eine are the Wiebeck, the Leine, the Schwennecke, the Mukarehne and the Langetalbach. Southeast of Aschersleben the Eine discharges into the Wipper at an elevation of 93.7 metres (307 ft) above sea level.
The Eine gives its name to the Wipper-Eine collective municipality.