The man died when the car he was travelling in collided with a tractor at Cloonart, Bornacoola at around ten-to-midnight last night.
The man was taken to Mullingar Hospital where he was pronounced dead.
The driver, and another two occupants in the car were also brought to Mullingar Hospital – where one of the passengers is being treated for serious injuries.
The driver of the tractor was uninjured.
This stretch of road is currently closed to facilitate a forensic examination.
Diversions are in place via Roosky for traffic coming from Sligo, and Newtownforbes for traffic travelling from Dublin.
Anyone with information is asked to contact Longford Garda Station.
