The man is being treated at Beaumont Hospital, where his condition is understood to be serious.
A man in his 20s is in hospital with a head injury following an assault in Dublin city centre last night.
Gardaí were alerted to a disturbance involving a group of men outside a premises on Usher's Quay shortly before 9 o'clock.
The man is being treated at Beaumont Hospital, where his condition is understood to be serious.
The scene was preserved overnight and examined by scenes of crime officers.
Gardaí are appealing for witnesses to come forward.

Woman Caught On Laptop While Driving As National Day Of Action For Mobile Phone Distraction Takes Place
RTÉ Senior Management Due Before Oireachtas Committee Today
Man Dies After Road Collision In Carlow
Rent Prices Now 40% Above Pre-Covid Levels
Meta Employees To Find Out Today If They'll Be Affected By Job Losses
Minister Lawless Positive After Meeting With Transport Minister On The Progression Of DART+ South West
Over 100 People Gather In Dublin Following Death Of Congolese Man
Former Garda And Celbridge Man Paul Moody Sentenced To Four Years For Harrassment And Coercive Control Of Ex-Partner