A man riding a Suzuki motorbike and a woman driving a Peugeot were travelling towards Bolton-by-Bowland when they collided with a third vehicle - a second Suzuki motorbike, travelling in the opposite direction.
The incident took place near C J & J M Huyton at Bolton Peel Farm at 1.35pm on Sunday (May 17).
The rider of the second Suzuki, a man aged 59 from Sabden, suffered serious leg injuries and was taken to Royal Preston Hospital.
The rider of the first Suzuki, a 44-year-man from Adlington, sustained a minor injury to his hand and did not need hospital treatment.
The Peugeot driver, a woman aged 27 from Blackburn, was not injured.
Sgt Lee Harris, of Lancashire’s Tactical Operations Division, said: "The man taken to hospital has suffered life-changing injuries and our thoughts are with him and his family at this difficult time.
"We are appealing for witnesses to establish exactly what happened. If anyone saw the collision, or any of the vehicles prior to the incident - or if you have CCTV or dash cam footage of the collision - please get in touch."
Anyone with information should contact police by calling 101, quoting log number 695 of May 17.
Alternatively, you can email [email protected]