The crash happened between 10pm and 11.20pm on a rural road in Westmeath.
A man in his 20s lost his life in the incident, and a teenage girl is said to be seriously injured in hospital.
It's reported the car left the road and ended up in a field near Mullingar in Co. Westmeath.
The man was taken to Midlands Regional Hospital in Mullingar where he was pronounced dead.
The road has been closed for a technical examination. Diversions are in place.
Gardaí are investigating and have appealed for any witnesses or anyone who travelled on that stretch of road between 10pm and 11.20pm to contact Mullingar Garda Station at 044 9384000, the Garda Confidential Line on 1800 666 111 or any garda station.
