The campaign for Sunday's elections has been marred by one of the most sweeping efforts in Egypt to silence critics, including new regulations on media coverage and a heavy-handed security clampdown on political opponents.
The ruling party is expected to secure a majority despite mounting opposition. Police and armed gangs have broken up campaign events by the government's top rival _ the Muslim Brotherhood.
To evade the police, organizers of Friday's rallies _ dubbed "Day of Anger" _ got the word out on Facebook and Twitter and locations were announced at the last minute via text messages.
In one protest in Cairo, about 200 protesters descended on the alleys of a low-income neighborhood, banging pots and pans and blowing horns.
They carried posters reading "Stop killing us" and held pictures of victims of police brutality.
"There are no guarantees to ensure the elections won't be rigged," said organizer Mostafa al-Nagar. He said the police have a free rein to crack down.
Similar protests were held in 10 other governorates.
Protesters dispersed before police arrived. But in Cairo, at least two protesters were nabbed as they left the rallies, al-Nagar said.
Opposition activists have used police brutality as a rallying point, particularly after the death in June of a young businessman from Alexandria, Khaled Said. Witnesses say plainclothes police dragged him from a cafe and beat him to death on the sidewalk.
Two policemen are on trial in the killing, but the government maintains that Said died of suffocation after swallowing a packet of drugs. Photos were circulated on social networking sites showing Said's body covered with bruises, his teeth broken and jaw smashed.
A Facebook page about Said that also serves as a sounding board for anti-government activists was shut down for a few hours on Thursday.
Popular pages on the social networking site for leading democracy advocate Mohamed ElBaradei and the Muslim Brotherhood were also blocked.
Activists blamed the government and its supporters.