A bomb explosion in the Imam Reza shrine in Mashhad, Iran, left at least 25 dead and more than 70 injured.

The Imam Reza shrine bombing refers to a bomb explosion that occurred on 20 June 1994 in a crowded prayer hall at the shrine of Ali al-Ridha, the eighth Imam of Shia, located in Mashhad, Iran. To maximize the number of casualties, the explosion took place on Ashura, one of the holiest days for Shia Muslims, when hundreds of pilgrims had gathered to commemorate the death of their third Imam, Husayn ibn Ali.

The Imam Reza shrine is a Shi'ite shrine, imamzadeh and mausoleum complex, located in the east of Mashhad, in the province of Razavi Khorasan, Iran. The shrine contains the grave 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.

Mashhad, historically also known as Mashad, Meshhed, or Meshed in English, is the second-most-populous city in Iran, located in the relatively remote north-east of the country about 900 kilometres from Tehran. In the Central District of Mashhad County, it serves as the capital of Razavi Khorasan province, the county, and the district. It has a population of about 3,400,000, which includes the areas of Mashhad Taman and Torqabeh.