The move by the Muslim Brotherhood - the country's strongest opposition force - and the smaller, secular liberal Wafd party is a blow to the attempts of President Hosni Mubarak's government to portray the country as a democracy.
Egypt's government has staunchly defended the fairness of last Sunday's election, despite reports by independent rights groups of blatant rigging in favour of the ruling party.
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Hide AdThe result will likely be a 518-seat parliament almost entirely made up of the ruling National Democratic Party, with a few seats going to independents and smaller parties.
The boycott was an unprecedented step by Egypt's opposition, which has for decades participated in elections that were consistently rigged, eager for the few seats they took each time. The move suggested deepening frustration with the domination of power by Mr Mubarak's ruling elite despite promises of reform.
"The ruling party is declaring itself as the only party in the country," said Abdullah al-Sinawi, an analyst and editor of the opposition Al-Arabi newspaper. "There is now a widespread sentiment that there is no use in trying to get this regime to reform."
The government was widely seen as determined to purge the Brotherhood from the legislature - particularly ahead of presidential elections next year, at a time when there are questions over the future of the country's leadership, after Mr Mubarak, 82, underwent surgery earlier this year to remove his gall bladder.