A parliamentary official said only 75 of the country's current total of 275 MPs were in the chamber on Sunday.
An appeals court had on Wednesday suspended a ban imposed on the candidates for alleged links to the Baath party.
The move could neutralise a major source of tension ahead of March 7 parliamentary elections.
The US had expressed fears that the large-scale blacklisting of candidates could undermine the credibility of polls.
Analysts also warned that the move could exclude Sunnis from politics and stoke sectarian tensions.
But hundreds of Iraqis staged a protest in Baghdad on Sunday, denouncing the court ruling to allow the candidates to contest the forthcoming elections.
Many of them carried placards that said, "No, No to Baath Party!" and "The return of the Baath Party [is] a return to mass graves."
After a committee tasked with de-Baathification blacklisted about 500 candidates, Jalal Talabani, Iraq's president, sought a compromise strategy by shifting the issue to the nation's highest appeals court.
The court then came up with a compromise of its own: the candidates could run, but would not be allowed to take office until their links to the former regime had been fully examined.
It was not clear, however, how many of the banned candidates would accept those rules.
Iraq's Shia-led government has pushed hard to weed out Saddam-era officials from public offices and security forces - a policy initiated by Washington shortly after the US-led invasion in 2003.
Many Sunnis believe the policy went too far, penalising innocent people who had to join the Baath Party to advance in their chosen careers.
The March poll comes at a critical juncture for Iraq, which is trying to put years of war that followed the 2003 US invasion behind it and revamp its economy by signing a raft of oil deals set to turn it into a top three oil producer.