Egyptian officials say initial results indicate voters have overwhelmingly approved a referendum on a new constitution. The outcome is seen as nudging army chief General Abdel Fatteh al-Sisi closer to a bid for the presidency.
Officials and state media said preliminary returns showed more than 90 percent of people who took part in the two-day vote said yes to the constitution supported by the military-backed government.
Observers have said there was little doubt the new charter would be approved. Official results are expected by the end of the week.
Election monitors reported Wednesday's voting was mostly trouble-free. Violence Tuesday between backers and opponents of ousted president Mohamed Morsi killed at least nine people.
The pro-Morsi Muslim Brotherhood and other Islamist groups boycotted the referendum, calling it illegitimate, leaving traditional Islamist strongholds across Egypt seeing only a trickle of voters.
Egypt's interior ministry indicated it had arrested more than 400 people, many of them Muslim Brotherhood supporters, for carrying weapons and other infractions during the referendum.
The new constitution would replace the pro-Islamic charter adopted in 2012 under Mr. Morsi. It strips away Islamist language and would give women greater rights and strengthen the power of the military.
If approved, this week's referendum would be followed by elections for a new president and parliament. Sisi - who ousted Mr. Morsi last year - is widely seen as a presidential favorite.
Authorities have since cracked down on Mr. Morsi's Muslim Brotherhood, declaring it a terrorist group and arresting many of its leaders. The former president and others are on trial for allegedly inciting violence that led to the deaths of protesters.