Police closed a section of Bradford Road after a motorcyclist came off his bike in Batley Carr this morning (Thursday).
The man in his 30s suffered serious injuries to his lower body.
Emergency services were called to the incident near Redbrick Mill at 8.30am.
The motorcyclist was treated by paramedics before being taken to Leeds General Infirmary.
The road is closed between Town Street and Howard Street while investigations continue.
A police spokesman said no other vehicles had been involved.