The database Íslendingabók contains genealogical information about the inhabitants of Iceland, dating back more than 1,200 years. Íslendingabók is a collaboration project between deCODE genetics, a research company in the field of medical genetics, and Friðrik Skúlason, an anti-virus software entrepreneur. The project's goal is to trace all known family connections between Icelanders from the time of the settlement of Iceland to present times and register the genealogical information in a database.

In the creation of the Íslendingabók database we have used various sources and both unpublished and published documents. Most of the genealogical information comes from sources such as church records, national censuses, inhabitants registers and other public documents, but in addition to these sources there are chronicles, books of convictions, various publications on genealogy, books about individuals within specific occupations, lists of descendants and ancestral records as well as memorial articles to name but a few.

The database is in Icelandic and is unfortunately not available in other languages.

Access to the genealogical database Íslendingabók is currently limited to Icelandic citizens and legal residents of Iceland who have been issued an Icelandic ID number (kennitala).