Police are appealing for witnesses following a collision on Bridge Road, Horbury Bridge on Monday, May 28.
The incident happened at 4.25pm at the junction with the Di Bosco restaurant - previously the Ship Inn pub - and involved a blue Suzuki motorcycle and a white Mini Cooper car.
The motorcycle was travelling in the direction of Wakefield.
As a result of the incident the rider of the motorbike was left with serious injuries, police said.
Any witnesses are asked to call police on 101 quoting log 1320 of Monday, May 28.
Alternatively, people can use a live chat system on the Contact Us section of the West Yorkshire Police website.