The polls have closed in the first round of voting in a referendum on Egypt's controversial new constitution.
Half of Egypt's eligible voters cast ballots Saturday on the draft constitution that has sparked weeks of violence and protests.
Men and women are voting separately at schools in Cairo and nine other provinces. President Mohamed Morsi has already cast his vote.
Long lines outside polling stations prompted election officials to extend the vote by four hours.
On Saturday, an opposition coalition accused the Muslim Brotherhood, which supports the proposed constitution, of rigging the vote. Mr. Morsi is a member of the Muslim Brotherhood.
The rest of the country will vote next Saturday . The vote has been scattered over two consecutive Saturdays "due to a boycott by a majority of the judiciary," which must oversee the vote by law.
It is not clear when final results will be announced.
Members of the liberal, secular and Christian opposition note the constitution will erode civil liberties because it rests on Islamist Sharia law and does not mention women's rights.
Officials say they have deployed 120,000 soldiers to protect polling stations.
Clashes broke out Friday among stone-throwing demonstrators protesting the draft constitution near a mosque in the port city of Alexandria, while police fired tear gas. Medical workers say 15 people were injured.
A largely Islamist committee approved the document last month.