Special aviaries have been built within the fortress for the birds - Baldrick, Bran, Branwen, Gundulf, Gwyllum, Hugine, Munin and Thor - as avian influenza spreads across Europe.
The tower's yeoman raven master, Derrick Coyle, said: "Although we don't like having to bring the tower ravens inside, we believe it is the safest thing to do for their own protection, given the speed that the virus is moving across Europe.
"We are taking advice on the vaccinations against avian flu, and in the meantime, we will continue to give our six ravens as much care and attention as they need."
The tower, a major tourist attraction, was founded in the 11th century.
Mindful of the legend, 17th century king Charles II decreed that the tower must always house at least six ravens - birds of ill omen. To prevent the ravens from flying away, their lifting feathers are trimmed.