Father-of-three Aidan Gahan, 57, from Glenbrien, near Enniscorthy in Wexford, was attacked in the early hours of April 9 while on the way home from a night out with his wife.
He was initially treated at Wexford General Hospital but, after slipping into a coma, was transferred to Beaumont Hospital in Dublin later on Easter Monday.
He remained on a life support machine since then, but his condition worsened in recent days and he died yesterday morning.
Mr Gahan owned a mini-market and petrol station in the village of Glenbrien.
The attack occurred after Mr Gahan and his wife had enjoyed a night in McCormack’s Bar with some other local people.
He was severely beaten and kicked in the head in the pub car-park after they left the premises.
No arrests have yet been made in the case.
Meanwhile, gardaí in Thurles have received a “very good response” following their appeal forinformation on the murder of a man whose body was found in a field on Sunday night.
The identity of the man, believed to be in his 30s, has yet to be established.
The inquiry was upgraded to a murder investigation after a post-mortem examination revealed that he had suffered a number of stab wounds.