The incident occurred on Sunday.
Gardaí in Donegal are investigating a single vehicle fatal road traffic collision involving a quad bike.
The incident took place on Sunday (16 June).
The driver of the quad bike, a man in his 40s, sustained serious head injuries when he came off the vehicle at approximately 7pm.
He had been travelling on a local road at Mullinboys near Mountcharles.
Following the accident, he was taken by ambulance to Letterkenny Hospital and later transferred to Beaumont Hospital where he has since passed away.
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