Gardaí are asking for witnesses to come forward following an assault in the city centre last night.
A man in his 20s is in hospital with a head injury following the incident.
Gardaí were made aware of a disturbance outside a premises on Usher's Quay shortly before 9 o'clock. Several men were reportedly involved.
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 asking anyone with information to contact them.