The Matenadaran, officially 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 expanded 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 word մատենադարան, matenadaran is a compound composed of մատեան, matean ("book" or "parchment") and դարան, daran ("repository"). According to Hrachia Acharian both words are of Middle Persian (Pahlavi) origin.Though it is sometimes translated as "scriptorium" in English, a more accurate translation is "repository or library of manuscripts." In medieval Armenia, the term matenadaran was used in the sense of a library as all books were manuscripts.

Some Armenian manuscript repositories around the world are still known as matenadaran, such as the ones at the Mekhitarist monastery in San Lazzaro, Venice and the Armenian Patriarchate of Constantinople, and the Vatche and Tamar Manoukian Manuscript Depository at the Mother See of Holy Etchmiadzin. To distinguish it from others, it is often referred to as the Matenadaran of Yerevan, the Yerevan Matenadaran or Mashtots Matenadaran.