Police are appealing for witnesses after a road traffic incident on the A647, Stanningley bypass.
The incident happened earlier today (Monday) at 9.40am and involved a Honda Civic.
It is believed the driver had a suspected medical episode at the wheel. He was taken to hospital in a serious condition.
No one else was injured during the incident.
Any witnesses to the incident – and in particular the movements of the vehicle prior to the incident are asked to call police on 101 quoting log 393 of today.