He had been in hospital since Monday.
A man in his 20s has died following a collision in Westmeath monday morning.
The incident happened in the Lough Ennell area of Mullingar at around 10.30am.
The man was an occupant in the car and was taken to Tallaght Hospital in a critical condition, where he has since passed away.
Nobody else was injured in the incident.
The driver of the car, a man in his late teens, was arrested at the scene for road traffic offences.
He has since been released without charge and a file will be prepared for the Director of Public Prosecutions.
Gardaí in in Mullingar are appealing for anyone who was in the Tudenham Park and Lough Ennell areas between 10am and 11am on Monday, 19th July 2021 and has any information or footage (including dash cam) to come forward.
Anyone with information can contact Mullingar Garda Station on 044 9384000 or the Garda confidential line on 1800 666 111.