The Chicago Police Department says 90 people were arrested before and during the NATO Summit.
Police spokeswoman Carolyn Deming also said eight police officers were injured while monitoring demonstrations and keeping protesters away from McCormick Place, site of the conference.
Chicago police Superintendent Garry McCarthy said Monday the news is what did not happened during the summit. He called the demonstrations a "non-event," adding that is supposed to happen in America.
Authorities say many of those arrested were released Monday without charges being filed.
McCarthy also said the officer stabbed in the leg during a clash Sunday between some demonstrators and police was treated and beck on the job shortly afterward.