GARDAI estimate 12,000 people are taking part in a demonstration in Waterford city, protesting about health cuts and other issues.
The protest is the largest in the city in decades and is causing major traffic problems.
The protest is taking place on the city’s quays, as the crowd is too large to fit in John Robert's Square.
One of the main issues concerns proposalss to downgrade Waterford Regional Hospital.
It was recently reported that an expert group is to recommend the break-up of the south-east hospital network.
This, according to reports, would see some services transferred from Waterford Regional Hospital to Cork.
The group is said to have suggested linking the hospital in Waterford to the much larger Cork University Hospital.
Other proposals include aligning Wexford General Hospital and St Luke's General Hospital in Kilkenny with counterparts in Dublin.
The recommendations are expected to be made to Health Minister James Reilly.
Traffic disruption is expected to continue until at least 3pm.
Speaking after the rally today Sinn Fein Senator David Cullinane said: “The downgrading of Waterford Regional Hospital will decimate services such as cancer care, trauma and cardiology. It will force patients from across the Southeast to travel to Cork and Dublin to hospitals already stretched from cutbacks. It will cost lives and cost jobs."
Mr Cullinane marched with his wife, councillor Kathleen Funchion, and their two sons.
They have argued the downgrading of the hospital would strip vital services and hit young and old people across Waterford, Wexford, Carlow and Kilkenny.