Fifty political parties and forces are commemorating last year's Mohamed Mahmoud Street clashes with marches to Tahrir Square.
University students began marching from Cairo University to Tahrir Square in mid-afternoon to mark the anniversary.
Stages have been erected in the square by the Revolutionaries of Egypt, the National Assembly for Change, Ultras Ahlawy and Kefaya.
The liberal Wafd Party, Popular Socialist Alliance Party, April 6 Youth Movement, Constitution Party, Maspero Youth Coalition, and Shayfenkom are also taking part in the memorial event.
Around 47 protesters were killed during four days of street clashes last November that erupted after the Central Security Forces tried to violently disperse a peaceful sit-in in Tahrir Square.
The commemoration starts on Monday and will continue until Friday. Each day activists will march from a different location to Tahrir Square and Mohamed Mahmoud Street.
The Second Revolution of Rage group has called for a march on Monday from the school in Sayyida Zeinab attended by one of the slain protesters to Mohamed Mahmoud Street. A second protest will take place on Qasr El-Nil bridge at 5:30pm to remember those who suffered eye injuries duing the clashes.