Peršėkė is a river in southern Lithuania; a left tributary of the Nemunas River.
It begins in the vicinity of the village of Gervėnai in Lazdijai District.
In its upper reaches, it flows through Lake Obelija and then continues northwest. After the confluence with the Gluosinė River, it turns northwest. In the lower reaches, it flows north and joins the Nemunas River bend near Balbieriškis.
Tributaries: Metelytė, Atesė, Gluosinė, Varputys, Rudė, Kamaria, Vaičiukupis (left-bank); Paežerėlė, Rudė II, Dūmė (right-bank).
The Peršėkė basin contains several lakes – Obelija, Metelys, Atesys, Angininkai Lake.
The valley is typically 200–300 meters wide, with valley slopes rising 9–12 meters. The riverbed width is 3–5 meters in the upper reaches, and 6–8 meters in the middle and lower reaches. The flow speed is 0.2–0.4 meters per second. The riverbed gradient is 120 cm/km. Spring floods are short and sudden, with the water level in the lower reaches rising by 3 meters. The Peršėkė River near Krokialaukis is dammed to form a 78-hectare reservoir.
