It happened around 10:28 Friday night near the intersection of SR 202 at Stanton Avenue in Westtown Township.
24-year-old Liam Crowley was riding a motorcycle, travelling north on SR 202 when a pickup truck turned in front of him.
The motorcycle crashed into the passenger side of the truck.
Crowley was injured and taken to Paoli Hospital in critical condition.
Police say the driver of the pickup, 49-year-old Robert Elwood Landis, showed signs of intoxication and failed a series of sobriety tests at the scene.
He was arrested and faces DUI and other related charges.
Meanwhile the accident remains under investigation.
Westtown-East Goshen police are seeking witnesses. Anyone with information can call 610-692-5100.