Dairy farmers are to gather outside the Scottish Parliament to protest against the prices they are paid for milk.
The farmers will lobby for a greater share of profit margins to help them afford production costs.
The National Farmers Union in Scotland said the amount paid to producers had fallen by 20%, or almost 4p per litre, since the start of 2009.
The protests coincide with a day of action for dairy farmers in more than 10 countries across Europe.
The farmers hope to meet MSPs during the gathering in Edinburgh.
Ian Smith, acting chairman of industry body Dairy Farmers of Scotland, said domestic milk production was at its lowest level since 1972.
"We are a net importer where we used to be a net exporter," he told BBC Scotland.
"The predictions are that by 2030 we will be importing over 50% of our dairy consumption.
"More and more dairy farmers are going to hit the wall. Many are already in the red."
He called for ministers to get involved, forcing retailers to change their practices.
He added: "The milk supply chain is not functioning in the long-term interest of the industry or the consumer.
"A long-term and transparent grocery supply chain code of practice and an ombudsman to enforce the code is essential."