Lake Balkhash (Kazakh: Балқаш Көлі, Balqaş köli; Russian: Озеро Балхаш, Ozero Balkhash) is one of the largest lakes in Asia and 15th largest in the world. It is located in Central Asia in southeastern Kazakhstan and belongs to an endorheic (closed) basin shared by Kazakhstan and China, with a small portion in Kyrgyzstan. The basin drains into the lake via seven rivers, the primary of which is the Ili River, bringing the majority of the riparian inflow; others, such as the Karatal, provide both surface and subsurface flow. The Ili is fed by precipitation, largely vernal snowmelt, from the mountains of China's Xinjiang region.

The lake currently covers an area of about 16,400 km2 (6,300 sq mi). However, like the Aral Sea, it is shrinking as a result of the diversion of water from rivers that feed it. The lake is divided by a strait into two distinct parts. The western part is fresh water, while the eastern half is saline. The eastern part is on average 1.7 times deeper than the western section. The largest city near the lake is also named Balkhash and has about 66,000 inhabitants. Major industrial activities in the area include mining, ore processing and fishing.

While the size of the lake is temporarily growing, there is concern about the lake's shallowing due to desertification and industrial activity.