The Barsakelmes State Nature Reserve (Kazakh: Барсакелмес мемлекеттік табиғи қорығы) is a nature reserve located in the Aral district of the Kyzylorda region in Kazakhstan.

The territory of the reserve consists of two clustered sections: "Barsakelmes" and "Kaskakulon." The "Barsakelmes" section includes the former reserve area (16,975 hectares) and the drained lakebed, with a total area of 50,884 hectares (of which the core zone is 37,725 hectares, and the buffer zone is 13,159 hectares). The "Kaskakulon" section occupies 109,942 hectares (with a core zone of 68,154 hectares and a buffer zone of 41,788 hectares).

The flora of vascular plants in the reserve includes 278 species, including endemic Kazakh species: wormwood (Aral and branched), Pratov's orache, various species of jüzgün (curled, low-growing, Talibin's), and Borshchov's tulip.

The reserve is home to rare and endangered animal species, including those listed in the Red Book. These include ornithofauna species such as the curly pelican, white-eyed pochard, marble teal, little egret, whooper swan, mute swan, pied avocet, snake eagle, steppe eagle, griffon vulture, golden eagle, jackdaw, merlin, black-bellied sandgrouse, white-bellied sandgrouse, snipe, brown pigeon, and eagle owl. Among mammals, rare and endangered species include the gazelle (jeiran), Turkmen kulan, saiga antelope, striped hyena, rare dwarf jerboa, and long-eared hedgehog. The Kaskakulon section currently hosts the main populations of kulan and jeiran, thanks to the presence of freshwater sources.

The island fauna differs from the mainland fauna and is represented by smaller species. The island is home to 13 species of mammals, 202 species of birds, and 8 species of reptiles. Among the mammals of the reserve, there are rare species such as kulan, jeiran, and saiga antelope. Among the birds, species include the jackdaw (bustard-beauty), small and grey larks, rock thrushes, and yellow buntings.

"Barsakelmes" is the only reserve in Kazakhstan with extreme ecological conditions — it is located in the zone of the declining Aral Sea. In other words, it is in a zone of global environmental disaster.

In 2016, Barsakelmes was included in the UNESCO World Network of Biosphere Reserves, and one of its sections, "Delta," which consists of wetlands, is protected by the international Ramsar Convention.