The fatal collision happened at Tullaskeagh at around 7.30 yesterday evening.
The man suffered serious injuries and was removed to University Hospital Limerick where he was later pronounced dead.
A post-mortem on his body is being arranged.
A man in his 70s, who was driving the car in which the man who died was a passenger, and the three male occupants of the other vehicle were also taken to UHL – they suffered non-serious injuries.
The R445 westbound carriageway (the old N7) was closed at the Knock Road junction, Tullaskeagh, until around lunchtime to facilitate Garda Forensic Collision Investigators.
Gardaí are appealing for witnesses and anyone with information is asked to contact Nenagh Garda Station on 067 50450, The Garda Confidential Line, 1800 666111 or any Garda Station.
