The Democrat says he discovered his house had been ransacked when he arrived home Monday from Washington.
Cleveland police say the initial report indicated someone entered the home through a rear window and scattered some files but it appeared nothing was taken. It's not clear when the break-in occurred, and police have no suspects.
Kucinich wasn't up for re-election Tuesday. He lost to U.S. Rep. Marcy Kaptur in a hard-fought primary after they were put in the same district.
Detectives also are investigating a break-in Monday at House Minority Leader Nancy Pelosi's wine country home in northern California.
Police haven't said there's any connection between the two cases.