The 30-year-old was exiting the Grand Red Line platform around 9 a.m. when he got into an argument with someone who pistol-whipped him in the forehead, police said.
Two shots were also fired but no one was struck, police said.
The man was taken to Northwestern Memorial Hospital where he was listed in stable condition, police said.
No one is in custody as Area Three detectives investigate.
The attack happened hours after a 16-year-old boy was shot dead on the same block.