Gardai began a murder investigation on Saturday afternoon after a 25-year-old mother of two was stabbed to death in the Finglas area of Dublin.
The woman was discovered in a seriously wounded state found in Melville Drive, Finglas.
She was taken to Connolly Hospital but was pronounced dead there a short while later.
Later Gardai arrested a man known to the deceased and he is being held at Finglas garda station.
Members of the force were alerted after neighbours heard screaming and arrived as a man fled the scene.
The woman was treated by ambulance personnel at the scene and on the way to the hospital in bearby Blanchardstown.