Thousands of Egyptians have gathered in Cairo's Tahrir Square to demand faster reforms and swifter prosecution of former officials from Hosni Mubarak's toppled government.
Being dubbed the 'march of the Million', today's rally is expected to be the biggest demonstration since the fall of Mubarak on February 11.
Most political groups and parties including the Muslim Brotherhood, Egypt's most organised political grouping, backed calls for the protest to be staged across Egypt.
Hundreds of people gathered in Suez and the coastal city of Alexandria. Tahrir Square had filled up before Friday prayers at noon.
This time Egyptians are protesting against the military rulers, who they say are dragging their feet on government reforms.
Five months after Egypt's revolution, many of the groups behind the protest say few of its goals have been achieved.
Call for action
"Punishment for the killers of the martyrs", read one banner in Tahrir, which was the focal point for protests that drove Mubarak out of office after 30 years in power.
While another slogan said "Down with the field marshal", referring to the military commander, Mohamed Hussein Tantawi, who heads the army council which took over after Mubarak resigned.
Tantawi was Mubarak's defence minister for two decades.
"We want to change everything. The old regime has corrupted everything. We want to change the government and those in charge, the field marshal as well," Ehab Mohamed Mahmoud, a demonstrator, said.
"The field marshal is an integral part of the old regime," he said.
More than 840 people were killed in police action in the 18 days leading up to Mubarak's ouster.
Protesters complain that many important figures from Mubarak era are yet to be brought to justice.
Yousef Boutrous Ghali, the Mubarak regime's finance minister and Rachid Mohammed Rachid, its industry and trade minister are on the run and are being sought to be tried.
Mubarak's closest inner circle of Ahmed Fathi Sorour, the speak of parliament; Safwat El Sharif, the secretray general of the former ruling National Democratic Party (NDP) and Zakariya Zami, the presidential chief of staff are also under investigation.
Other key figures are Gamal Mubarak and Alaa Mubarak, the ousted president's sons, Ahmed Ezz, the former NDP executive member and Mubarak's close confidant Hussien Salam, who has been apprehended in Spain.