Apparatus, methods, and other embodiments associated with de-duplication seeding are described. One example method includes re-configuring a data de-duplication repository with a blocklet from a data de-duplication seed corpus. Reconfiguring the repository may include adding a blocklet from the seed corpus to the repository, activating a blocklet identified with the seed corpus in the repository, removing a blocklet from the repository, and de-activating a blocklet in the repository. The example method may also include re-configuring a data de-duplication index associated with the data de-duplication repository with information about the blocklet. Reconfiguring the repository and the index increases the likelihood that a blocklet ingested by a data de-duplication apparatus that relies on the repository and the index will be treated as a duplicate blocklet by the data de-duplication apparatus.