The stoning takes place in Mina, where Islam says Satan tempted the biblical patriarch Abraham.
The stoning of the pillars is among the most followed, and most dangerous, elements of the annual pilgrimage.
This year's stoning ritual tests new safety measures in place to avoid a tragedy similar to the scene in the last hajj, when 362 pilgrims were crushed to death.
Official figures suggest that nearly 2.5 million Muslims from 187 countries are participating in Islam's annual pilgrimage, more than 40 percent of them women.
(AFP)