Police said the victims all thought they had been talking to another female, and arranged to meet "her" in the South Shore neighborhood.
Instead, they were all confronted by a man who kidnapped each of them, took them somewhere else and raped them.
The man also robbed the victims.
The first attack happened on March 21 on South Euclid at 74th.
The other three attacks all happened on East 73rd Place on May 8, May 21 and May 27.
The description of the suspect is vague.
If you have information, Chicago police detectives would like to speak with you at (312) 747-8380.