This is a first part of the new catalogue of medical manuscripts preserved in the Wellcome Library. It serves not only as a guide to the collection of the manuscripts, purchased by the Wellcome Library in 1986, but is also an independent research tool, which can be used by various specialists: librarians, historians, paleographers, art historians, conservators, etc. This catalogue comprises detailed indices and many illustrations on cd-rom, which help researchers to consult in detail each codex prior to coming to the Wellcome Library in London to consult the manuscript per se.