They're protesting about a range of grievances - despite several measures announced by the government.
But what are the issues, and what could the government do next?
Agricultural workers in several EU nations have mounted protests.
In France, farmers say they are not being paid enough, and that they're being choked by excessive regulation on environmental protection.
Some of their concerns, like competition from cheaper imports and environmental rules, are shared by producers in the rest of the EU.
Other issues, like the food-price negotiations, are France-specific.
Pascal Desprez is a grain farmer.
"We're here because we're honestly unhappy with the current policies in terms of agriculture. We're especially overwhelmed with norms that prevent us from working and that lower our production yields. And so we're calling on President Emmanuel Macron to put in place more realistic norms, or even remove the norms altogether - that would be great progress."
Many feel that a push by the government and retailers to bring down food inflation has left them unable to cover high costs for energy, fertilizer and transport.
A government plan to phase out a tax break for farmers on diesel fuel was also a flashpoint.
Discontent about unfair competition in sugar, grain and meat has also spread.
Large imports from Ukraine, for which the EU has waived duties since Russia's invasion, are in part the cause of that.
The imports are resented for putting pressure on European prices, while not meeting environmental standards imposed on EU farmers.
Philippe Chalmin of Paris Dauphine University is an economist specializing in commodity markets.
"There is first a question of revenue, and it's clear that French farmers don't earn much. Second, and this is very French, this is the accumulation of rules, of norms, of everything that, that the farmers have now to comply with. And a third, kind of reaction, against what you would call 'agri-bashing' by town citizens, consumers who at the same time wants to have more natural products and more products coming directly from the farm, etc. But we are not really ready to pay for them."
Farmers take issue with EU subsidy rules, such as an incoming requirement to leave 4% of farmland fallow...
and what they see as France's overcomplicated implementation of EU policy, such as in restoring hedges.
Green policies are also seen as contradicting goals to become more self-sufficient in production of food and other essential goods, in light of the Ukraine war.
Disagreements over irrigation projects and criticism about animal welfare and pesticides have heightened feelings among an ageing French farmer population of being disregarded by society.
Time is ticking for the government, which is under pressure to defuse the crisis ahead of June elections and the annual Paris farm show in late February.
Prime Minister Gabriel Attal announced the scrapping of diesel tax increases for farmers on January 26.
He also aims to reduce red tape, and offered extra aid to some groups of farmers.
Initial announcements drew mixed reactions and farmers' unions have called for protests to continue.
The French government has, so far, been tolerant towards protesters despite some violent incidents.
But it has ordered police to protect Paris' airports and the wholesale food market after calls for them to be targeted.
