After decades of authoritarian rule, Egyptians are for the first time freely choosing their first president since last year's ousting of long-time ruler and close US ally Hosni Mubarak.
Voters lined up as polls opened at 8am local time (6a Irish time) across the nation of 82 million people.
Thirteen candidates, who include Islamists, liberals and Mubarak regime figures, are contesting the election.
No outright winner is expected to emerge from the two-day vote so a run-off between the two most popular candidates will be held on June 16 and 17. The winner will be announced on June 21.
The generals who took over from Mr Mubarak when an uprising forced him to step down have promised to hand over power by July 1.