Hermione Granger's file is a file kept by the Ministry of Magic while it was under Lord Voldemort's control in 1997. It was kept on Dolores Umbridge's office.
The document listed Hermione's blood status, the status of her family, and her security status. Because she was a Muggle-born and a friend of Harry Potter, "Undesirable Nō. 1", she was tracked.