The announcement on Tuesday concerns an amendment referendum on 25 May that could allow for the first competitive presidential polls in the country, but the politicians say it is flawed.
"The three parties announce that they will boycott the 25 May referendum on the constitutional amendment and call on the Egyptian people to boycott it and stay home that day," the parties said in a joint statement.
The centre-liberal Wafd, the Marxist party, Tagamu, and the Nasserist Party say the new conditions for registration are so strict that only the ruling National Democratic Party (NDP) will be able to field a candidate, undermining the whole point of the reform.
The Muslim Brotherhood later issued a statement in which it called for a boycott "in agreement with the position of parties and national political forces which refuse to participate" in the referendum.
The group has been banned since 1954, but has been tolerated, with 17 MPs sitting as independents in parliament. Egyptian analysts estimate it could get as many as 30% of seats in a free and fair elections.
Egypt's lawmakers, facing mounting calls for reform from both institutional parties and other secular and Islamist opposition groups, approved the amendment on 10 May.
Hosni Mubarak has ruled Egypt
uninterruptedly since 1981
Under the proposed changes applying to the next polls due in September, independents must collect 250 signatures from MPs, senators and representatives in local councils which are dominated by President Hosni Mubarak's NDP.
The following elections in 2011 will further require that political parties field candidates only five years after coming into existence. They should also hold a minimum of 5% of seats in both houses of parliament.
Wafd, Tagamu and the Nasserist Party also announced they would no longer take part in a dialogue called by the NDP on democratic reforms backed by Washington.
"The NDP rejected every proposal advanced, notably pertaining to the constitutional amendment," their statement read.