Police said the crash happened in the South Shore neighborhood's 6900-block of South South Shore Drive just after midnight.
A 36-year-old man was driving northbound in the southbound lane when he struck another vehicle, driven by a woman, police said.
Police said both drivers were taken to the University of Chicago Medical Center in critical condition.
Two female passengers in the woman's vehicle suffered minor injuries, and were taken to Trinity Hospital in stable condition, police said. Their ages were not immediately known.
No other injuries were reported and CPD's Major Accident Unit is investigating.