On 31 July 1987, during the Hajj pilgrimage in Mecca, a clash between Shia pilgrim demonstrators and the Saudi Arabian security forces resulted in the death of more than 400 people. The event has been variously described as a "riot" or a "massacre". It developed from increasing tensions between Shia Iran and Sunni Saudi Arabia since the 1979 Iranian Revolution. Since 1981, Iranian pilgrims have held a political demonstration against Israel and the United States every year at Hajj, but in 1987, a cordon of Saudi police and the Saudi Arabian National Guard sealed part of the planned demonstration route, resulting in a confrontation between them and the pilgrims. This escalated into a violent clash, followed by a deadly stampede.

There have been numerous incidents during the Hajj, the Muslim pilgrimage to the cities of Mecca and Medina, that have caused loss of life. Every follower of Islam is required to visit Mecca and Medina during the Hajj at least once in their lifetime, if able to do so; according to Islam, the pilgrimage is one of the Five Pillars of Islam. During the month of the Hajj, Mecca and Medina must cope with as many as three million pilgrims.