The Irish Farmers Association say they will continue staging protests until there is a substantial increase in beef prices.
The latest 12-hour blockade is taking place outside Tesco's main distribution centre in Donabate, north county Dublin.
Tesco have said that today's action is regrettable.
Products are usually driven from this hub - which is the size of 10 football pitches - to Tesco stores across the country.
But since 7am, a group of around 30 farmers have stopped any trucks getting in or out.
"We've had enought of it," said one farmer.
"We're not going to sit down and take this anymore. The abuse of farmers is over."
Today's demonstration is part of the long-running dispute over beef prices.
On Friday, one of the largest beef processors in the country, ABP, announced it would increase the base price it pays for cattle from today.
But the IFA says the suggested rise of between 5 and 10c a kilo isn't enough.
The organisation says more protests will follow unless there is a significant price increase.
Earlier: Farmers protesting outside Tesco Distribution Centre in Dublin
A group of farmers are protesting outside the Tesco Distribution Centre in Dublin.
The latest demonstration is taking place at Tesco's main distribution centre in north county Dublin.
Around 30 protesters have used a tractor and trailer to stop trucks getting in or out of the Donabate site.
@IFAmedia members staging a protest this morning outside the Tesco distribution centre in Donabate, Co. Dublin. Access to the site has been blocked in a protest to raise beef prices pic.twitter.com/sbve42xLa4— Agriland (@AgrilandIreland) December 9, 2019
Tesco have said this morning's blockade is "regrettable".
The Irish Farmers Association has accused retailers like Tesco of "hiding" behind meat factories in the ongoing beef price dispute.
IFA President Joe Healy has said the current situation cannot continue.
"The retailers have kind of got away scot-free in all of this and they've a major role to play in what is without doubt a dysfunctional food chain," said Mr Healy.
"The farmer is the price taker. We see the retailers and we see the processors make huge profits and the farmers struggling to survive.
"The farmers are selling at up to 50c and more below the cost of production. And that's not sustainable."
Today's action is the latest in a series of blockades staged by the IFA over beef prices.
On Thursday, the IFA staged a blockade at the Aldi distribution centre in Naas, Co Kildare.
That was followed by a protest outside Lidl's centre in Charleville, Co. Cork.
The long-running beef price dispute saw ABP - one of the largest beef processors in the country - announce that from today the base price it pays for cattle would increase.
But the IFA says what is been offered is between 5 and 10c a kilo - which it hass described as "paltry".
The organisation wants a substantial price increase for farmers or more blockades, like the 12-hour one getting underway this morning, will follow.