The Imam Reza shrine (Persian: حرم امام رضا, romanized: Haram-e Emâm Rezâ, lit. 'Sanctuary of Imam Reza'; Arabic: العتبة الرضوية) is a Shi'ite shrine, imamzadeh and mausoleum complex, located in Mashhad, in the province of Razavi Khorasan, Iran. The shrine contains the remains of Ali al-Rida, who is regarded as the eighth Imam in Shia Islam. Also contained within the complex are the Goharshad Mosque, a museum, a library, four seminaries, a cemetery, the Razavi University of Islamic Sciences, and other buildings.

The complex is one of the holiest sites in Shia Islam, is a major Iranian tourism center, and has been described as "the heart of the Shia Iran" with 25 million Iranian and non-Iranian Shias visiting the shrine each year, as of 2007.

The shrine covers an area of 267,079 square metres (2,874,810 sq ft) while the seven courtyards which surround it cover an area of 331,578 square metres (3,569,080 sq ft), totalling 598,657 m² (6,443,890 sq ft).

The complex was added to the Iran National Heritage List on 6 January 1932, administered by the Cultural Heritage, Handicrafts and Tourism Organization of Iran, and, on 2 February 2017, was added to the tentative list of UNESCO World Heritage Sites.