Thousands of protesters have gathered in Cairo's downtown Tahrir Square, demanding that Egypt's ruling military council hand over power to civilians.
Rival political parties of Islamists and liberal youth groups joined ranks despite months of bitter disputes and accusations.
Protesters chanted, "down with military rule."
Islamists captured nearly 70 percent of parliament seats in last year's elections. They have stayed away from most street protests, hoping for accommodation with the ruling generals, who took power after Hosni Mubarak's regime was ousted in a popular uprising last year.
In recent weeks the Islamists have demanded that the military fire the Cabinet it appointed and allow the parliament to form a new one, but the military has refused. Also, the main Islamist candidates for president were disqualified, stirring anger.