Mes Aynak (Pashto/Persian: مس عينک, meaning "little source of copper"), also transliterated as Mis Ainak or Mis-e-Ainak, was a major Buddhist settlement 40 km (25 mi) southeast of Kabul, Afghanistan, located in a barren region of Logar Province. The site is also the location of Afghanistan's largest known copper deposit.

The site of Mes Aynak possesses a vast 40 ha (100 acres) complex of Buddhist monasteries, homes, over 400 Buddha statues, stupas and market areas. The site contains artifacts from the Bronze Age, and some of the artifacts recovered have been dated to over 3,000 years old. The wealth of Mes Aynak's historical residents may still be seen in the remote site's far-reaching size and well-guarded perimeter. Archaeologists are only beginning to find remnants of an older 5,000-year-old Bronze Age site beneath the Buddhist level, including an ancient copper smelter.

The eagerness of Afghanistan's current Taliban government to unearth the copper beneath the site is leading to the site's destruction, rather than its preservation. Archaeologists have photographed the site and relics have been excavated.

The word Mes Aynak (مس عينک) literally means "little source of copper"; mis (مس) is "copper", while aynak (عينک) is a diminutive form of ayn (عين), which means "source".

As its name suggests, the presence of copper at Mes Aynak has been known about for some time, while the site's archaeological wealth had been discovered by Russian and Afghan geologists in 1973–1974.

Mes Aynak was at the peak of its prosperity between the 5th and 7th centuries AD. Coins of the Alchon Hun rulers Khingila and Mehama were found here, which confirms the Alchon presence in this area around 450-500 CE.

A period of slow decline began in the 8th Century, and the settlement was finally abandoned 200 years later.

On 17 May 2020, the Taliban attacked a security checkpoint near the Mes Aynak mine. Eight security guards were killed and five others were wounded.