The Mesrop Mashtots Institute of Ancient Manuscripts is a museum, repository of manuscripts, and a research institute in Yerevan, Armenia. It is the world's largest repository of Armenian manuscripts. It was established in 1959 on the basis of the nationalized collection of the Armenian Church, formerly held at Etchmiadzin. Its collection has gradually risen since its establishment, mostly from individual donations. One of the most prominent landmarks of Yerevan, it is named after Mesrop Mashtots, the inventor of the Armenian alphabet, whose statue stands in front of the building.

The earliest mention of a manuscript repository in Armenia was recorded in the writings of the fifth century historian Ghazar Parpetsi, who noted the existence of such a repository at the Etchmiadzin catholicosate in Vagharshapat, where Greek and Armenian language texts were kept.

It was built in gray basalt from 1945 to 1958, however, construction was put on hold from 1947 to 1953 due to unavailability of skilled laborers and carpenters. Designed by Yerevan's chief architect Mark Grigorian, it is influenced by medieval Armenian architecture.