The crash occurred at about 9:36 p.m. in the 10700-block of West Irving Park Road.
Police said the victim was stopped on the road on the eastbound lanes with his semi-truck, which appeared to be disabled.
The victim was then struck by an unidentified vehicle which fled the scene, police said. He was transported to Lutheran General Hospital in critical condition.
No one is in custody and detectives are investigating, police said.