It happened just before 9 p.m. in the 1100-block of North Rush Street in the Gold Coast, Chicago police said.
The victim was stabbed in the abdomen after getting into an argument with another man, CPD said.
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Chicago fire crews took him to Northwestern Memorial Hospital in critical condition.
No one is in custody, as Area Three detectives investigate.
Chicago police said the suspect in the stabbing is about 50 years old, with gray hair and a white T-shirt.