The Petrova Book is history book about the Petrova Family. It was written that the Petrova line had ended with Katerina Petrova, though this is untrue because Katerina had an illegitimate child and therefore the Petrova bloodline has continued. Elena Gilbert was actually the last of the Petrova bloodline, being one of Katerina's descendant.
It is first seen in the episode Bad Moon Rising, when Damon Salvatore took it from the shelf at the Duke University and gave it to Elena. In the episode Katerina, Elena brought it to Katherine in the tomb and said that the book is actually on Petrova family history. Katherine found a photo of her family in the book stuck in between two of the pages. It is written in Latin.
- The name Petrova comes from Katherine's birth name which was originally Katerina Petrova. It is stated that after she was turned, she changed her name from Petrova to Pierce, to prevent being found by Klaus.