The incident occurred at about 2:13 a.m. at the hotel in the 300-block of East Wacker Drive.
Police said a 30-year-old woman was stabbed by a female suspect during a fight in the lobby.
The victim was cut on her head, arm and as well as multiple wounds on her back. She was transported to Northwestern memorial Hospital in fair condition.
The suspect fled the scene and is not in custody. Area Three detectives are investigating.