Four people have been killed in Egypt during clashes betwen police and protesters on the second anniversary of the revolution.
Police fired tear gas to disperse thousands of opponents of President Mohamed Morsi, gathered in Cairo's Tahrir Square.
At least 186 people and 45 security personnel were hurt during protests in various cities, including Cairo, Alexandria and Suez, according to medics. The fatalities were in Suez.
In Ismailia, hundreds of demonstrators broke into local government offices after the headquarters of the Muslim Brotherhood in the city were set ablaze.
On Thursday, clashes erupted after protesters tried to dismantle a wall of concrete blocks closing a street leading to the square.
The secular-leaning opposition has called for mass protests against Mr Morsi and his party, the Muslim Brotherhood, using the same slogan that brought Egypt to its feet in 2011 and ousted Hosni Mubarak: "Bread, freedom, social justice."
Opposition leader and former head of the UN's atomic agency, Mohamed ElBaradei, wrote on his Twitter account: "Go out into the squares to finally achieve the objectives of the revolution."
Tahrir Square is the iconic birthplace of the 2011 revolution, and demonstrators gathered in front of the presidential palace, where anti-Morsi rallies last December erupted into deadly clashes with Islamist supporters.
The Muslim Brotherhood has not officially called for its own rallies, instead marking the anniversary by launching a charitable and social initiative called: "Together we will build Egypt."
Mr Morsi urged Egyptians to spend the anniversary in a "peaceful and civilised way" in a speech on Thursday to mark the birthday of the Prophet Mohammed.
The violence broke out ahead of a court verdict due on Saturday in the trial of dozens of defendants over the worst football disaster in Egyptian history.
More than 70 people were killed in Port Said in February last year during clashes in the Suez Canal city between fans of home side Al Masry and diehard supporters Cairo's Al Ahly, known as Ultras.
Al Ahly supporters warned of violent protests and a "new revolution" if Saturday's verdict goes against them.