The Irish Farmers Association says Brexit has so far cost beef farmers over €100m.
They say price cuts brought on by Brexit have left many on the brink of going out of business.
A protest to highlight their concerns is taking place outside a meeting of Cabinet in Cork later.
IFA President Joe Healy says beef farmers are suffering and the Government needs to act like they said they would.
"The minister has adopted a wait and see approach and this government has said that they'd have farmers' backs in the case of Brexit - well know we want them to back up their words," said Mr Healy.
"We don't have to wait and see. Farmers have endured the pain of Brexit in their pockets, where it really hurts."
"Unless they're supported they'll go out of business."