A man has been arrested in connection with an assault that left the victim on a life support machine in Waterford.
The incident happened in the early hours of yesterday morning in the Barker Street area of the city centre.
It is believed that the injured man was struck a number of times.
The victim was brought to Waterford Regional hospital with head injuries and was last night said to be in a critical condition.
Anyone with any information about the incident is asked to contact Waterford Garda station.
Meanwhile, gardaí in Cork are appealing to witnesses to a serious assault which took place in the early hours of this morning.
A man in his early 20s was assaulted near the fountain on Grand Parade at about 3am. He was taken to Cork University hospital.
Gardai are appealing for witnesses who may have been in the vicinity of the Grand Parade Cork between 2am and 3am or any person with information to contact them at Anglesea Street Garda station on 021-4522000.