The motorcyclist, a man from Evesham, has been taken to Frenchay Hospital in Bristol with life threatening injuries.
A 20-year-old man from Apperley has been arrested on suspicion of driving without due care and attention. He is currently helping police with their inquiries.
The A435 at Gotherington remains closed following the incident.
The collision happened at around 8am and involved a red Yamaha motorcycle and a silver Peugeot 306.