On Monday the demonstrators from the Kefaya Movement also condemned the deaths of 12 people in violence during the elections, which took part in three stages over a month and ended last week.
George Ishak, a Kefaya coordinator, said: "This is the first protest after the elections, against what happened in the elections - the forgery and the beatings that occurred."
Monitoring groups said the ruling National Democratic Party (NDP) widely resorted to bribery and coercion to secure votes.
Riot police blocked polling stations in areas where opposition candidates, predominantly from the Muslim Brotherhood, had strong support. The Brotherhood won nearly 20% of the seats.
Security forces also harassed and beat journalists and confiscated their equipment. The authorities blamed violence on supporters of opposition candidates.
The demonstrators began their protest in front of a court in central Cairo before marching in nearby streets.
They called for the resignations of Hosni Mubarak, the Egyptian president, and Habib el-Adli, the interior minister, and carried a coffin on which was written: "Funeral of the elections."
"The legislative elections, despite their flaws, are an important step forward in the march towards political and democratic reform"
Abdel Halim Kandil, a Kefaya spokesman, said: "This return to the street is for the simple reason that the route of change through elections is blocked."
Kefaya, a loose grouping of political pro-reform activists, sprang up last year to campaign against a fifth six-year presidential term for Mubarak or any transfer of power to his son Gamal.
Mubarak won a re-election in September with 88.6% of the vote.
Meanwhile, on Monday, Mubarak conceded there had been "flaws" in recent parliamentary elections but hailed the polls as a major step towards democratic reform.
"The legislative elections, despite their flaws, are an important step forward in the march towards political and democratic reform," he was quoted as saying by the official Mena news agency.