A motorist was killed in the early hours of Thursday morning in a collision outside Carrick-on-Suir.
A second car involved in the accident failed to stop and Gardai are now trying to trace it.
It's the second fatal accident on South Tipperary roads this week.
On Tuesday a man in his 20s died in a single vehicle crash between Poulmucka and Barne, near Clonmel.
Gardaí in Thomastown, Co. Kilkenny are appealing for witnesses to Thursday morning's crash.
At approximately 1am a car collided with a second vehicle on the westbound carriageway of the N24 Piltown By Pass near Fiddown, on the Carrick-on-Suir to Waterford road.
The second vehicle failed to remain at the scene.
The driver and sole occupant of the car, a man in his 20s, was seriously injured. He was pronounced dead at the scene a short time later. His body has since been removed to University Hospital Waterford for a post-mortem examination.
The west bound carriageway of the N24 at the scene of the collision is currently closed to traffic and Garda forensic collision investigators will carry out an examination this Thursday morning. The local coroner has been notified.
Anyone with information is asked to contact Gardaí at Thomastown 056-7754150 or the Garda Confidential Line 1800 666 111.