He is being questioned at Kildare Town Garda Station.
A man in his mid 20s has been arrested as part of the investigation into the murder of David Boland in Co Kildare.
The 34-year-old was stabbed on Duke Street in Athy at 5.30am yesterday morning.
He later died at Midlands Regional Hospital Portlaoise.
Gardaí investigating the circumstances surrounding his death detained a "young man" from the Carlow area yesterday.
He is being questioned at Kildare Town Garda Station.
