Thousands of trade workers have walked off the job in Melbourne and Sydney to protest against the federal government's decision to force the CFMEU's construction arm into administration.
A sea of orange and yellow high-vis vests and hoodies formed outside Trades Hall on the edge of Melbourne's CBD, with workers waving CFMEU flags and chanting.
The Sydney rally began at Belmore Park, with members marching towards the state parliament house on Macquarie Street.
This is the second time the CFMEU has rallied in Sydney in recent weeks. (ABC News: Keana Naughton)
The federal government intervened last month in response to allegations of corruption and criminal infiltration into the union.
Media coverage of the allegations had led to Victorian branch secretary John Setka leaving his role in July.
The federal government is planning a meeting next month between unions, government and businesses, in a bid to reset in the wake of the CFMEU scandal.
In Melbourne, CFMEU national secretary Zach Smith raised concerns that the appointment of the administrator would lead to a reduction in wages and conditions.
"An attack on one union is an attack on all," he said.
"Our victory is assured if we stand together and fight together and today we will be sending a very clear message across those corporate board rooms, across the halls of parliament that we're drawing a line in the sand."
Thousands of people took to the streets in Sydney, starting in Belmont Park and marching towards state parliament. (ABC News: Keana Naughton)
Speaking at the Sydney rally, delegate Denis McNamara said he believed the government's intervention was unlawful.
"The federal government have taken over our union. They've put our union in administration with no proof," he said.
"You know, there's been allegations from the media, and from that, they've decided to put our whole union into administration."
Protesters in Sydney were told the administration process had been unfair. (ABC News: Keana Naughton)
Today's rallies follows marches that included tens of thousands of members of other trades unions, including the Australian Manufacturing Workers' Union, Electrical Trades Union and the plumbers' union, in Melbourne, Sydney, Adelaide, Brisbane, Cairns, Canberra, and Perth just weeks ago.
Police have urged those attending rallies to protest peacefully.
The Fair Work Ombudsman has advised employers to consult with workers on whether they intended to use available leave if they were absent from work today.