A 29-year-old man was airlifted to hospital after a crash with a lorry on the A43 between Corby and Geddington.
The man from Stamford was in a blue Vauxhall Corsa travelling towards Kettering when it was in collision with a Volvo lorry, driven by a 26-year-old man from West Bromwich.
The driver of the Corsa was taken by air ambulance to University Hospital Coventry with serious injuries.
The lorry driver was uninjured.
A spokesman for the Warwickshire and Northamptonshire Air Ambulance said: “The patient had suffered significant injuries to his face, head, pelvis and both legs.
“He was given extended pain relief and anaesthetised by the WNAA doctor.
“He was immobilised before being airlifted to University Hospitals Coventry & Warwickshire for further treatment.”
The incident was the 12,000th helicopter mission carried out by the air ambulance.
Police are appealing for witnesses to the crash which took place at 11.30am on Friday (February 7).
Any witnesses are asked to call the Drivewatch Hotline on 0800 174615 or Northamptonshire Police on 101.