The Lepsy (, Lepsi; ) also known as the Lepsa River or the Lepsi River, is a river in south-eastern Kazakhstan. It originates in the Dzungarian Alatau Mountains north of the border with China and flows into Lake Balkhash. The river is long and has a basin area of . The Lepsy is the easternmost of the two small rivers that flow into the eastern Balkhash on the south bank, the other being the Aksu. The Lepsy is one of the main rivers of the historic region of Zhetysu.