Gardaí investigating the fatal accident on the N11 at Ballylough, Ferns have arrested a man in his 30s in Wicklow Town this morning.
An 81-year-old man was fatally injured when the car he was driving was and a second vehicle were in collision at around 10.30pm on January 12.
The man was pronounced dead at the scene and his body was removed to Wexford General Hospital.
The female passenger aged in her 50s was brought Wexford General Hospital with injuries described as serious.
The two occupants of the second car did not remain at the scene.
The man who was arrested today is being detained at Enniscorthy Garda Station under the provisions of Section 4 of the Criminal Justice Act 1984.