Egyptian authorities say more than 500 people were injured after riot police and rock-throwing protesters clashed in Cairo's Tahrir Square.
The unrest unfolded over the day on Saturday as police fired tear gas and rubber bullets to try to disperse hold-outs from a mass protest on Friday.
The unrest was reminiscent of the anti-government protests that led to former President Hosni Mubarak's February departure.
The violence erupted just over a week before Egypt begins its first parliamentary elections since Mr. Mubarak's fall.
Tens of thousands of protesters jammed the square on Friday in reaction to a government proposal that would exempt the military from civilian oversight in the next constitution. Critics called the plan a military attempt to prolong its "temporary" powers.
The rally was called by the Muslim Brotherhood, the country's most organized political group.
Egyptians begin going to the polls on November 28 for parliamentary elections that will stretch into March.
The new legislature will draft a constitution ahead of presidential elections.
Some information for this report was provided by AP, AFP and Reuters.