The fight late on Thursday was violent even by the fractious standards of Ukraine's Verkhovna Rada and came amid tensions after a criminal probe was opened this week against opposition leader Yulia Tymoshenko.
Deputies from Tymoshenko's BYuT-Batkivschyna party and the Regions Party of President Viktor Yanukovych slugged it out for several minutes behind the speaker's chair leaving at least three opposition MPs injured.
"The deputies of our faction were brutally beaten up by the Regions Party and we will make a complaint so that those who committed this crime are brought to responsibility," said the head of the opposition faction Sergiy Sobolev.
Opposition deputy Mykhailo Volynets was taken away from the chamber on a stretcher with a serious head injury, his colleague Volodymyr Bondarenko received a wrist injury and fellow MP Yuriy Gnatkevych was hospitalised.
Reports said the fight started after opposition MPs blockaded themselves inside the chamber and hung banners protesting the legal action against Tymoshenko reading "Hands off Tymoshenko!" and "Stop Political Repression!"
Regions Party MPs then stormed into the chamber by breaking down the doors and were reported to have stayed in the hall overnight with the aim of ensuring security.
Former prime minister Tymoshenko, who lost a tight fight for the presidency to Yanukovych earlier this year, this week was forbidden to leave Kiev after a probe was opened against her on suspicion of abuse of power while in office.
Friday's session of the Rada got underway peacefully but with none of the opposition deputies present, an AFP correspondent reported.