The 16 year old was a passenger in a car which left the road between Ballingarry North and Cloughjordan yesterday afternoon.
The teenager was in the back of the car which went off the road and hit a tree at Boston around 3.45pm.
He was pronounced dead at the scene – his body was taken to University Hospital Limerick.
The two other occupants of the car – a 22 year old man and a 17 year old girl were also hospitalised.
The man is said to be in a serious condition.
The road was closed for a time to allow an examination of the scene by Garda Forensic Collision Investigators.
Anyone with information is asked to contact Nenagh Gardaí on 067 50450, the Garda Confidential Telephone Line 1800 666 111 or any Garda Station.
This latest fatality comes just days after 68 year old Michael Stapleton was killed in a hit & run near Glengoole.