Des Plaines police responded to the 1500-block of Miner Street around 12:15 p.m. for a report of a stabbing.
Officers said they found the victim, a 53-year-old Skokie man, standing in the road with multiple stab wounds.
The victim told officers he got into an argument with a cyclist, who reached into the vehicle and stabbed him with a knife.
The Des Plaines Fire Department transported him to a local hospital with serious injuries.
Police said the attack appears to be an isolated road rage incident.
The bicyclist, who fled the scene, is described as a man between 30 and 40 years old. He wore a grey tank top, khaki shorts, and a backpack.