The International Thylacine Specimen Database (ITSD) is the culmination of a major cooperative effort between museums and universities that hold specimens of the thylacine (Thylacinus cynocephalus), to produce the first comprehensive study of all that is known to physically remain of this unique species. The ITSD was first published in April 2005 as a digital resource on CD-ROM. It was subsequently revised in 2006 (2nd rev.), 2009 (3rd rev.), 2011 (4th rev.) and 2013 (5th rev.) The sixth revision (2017) will be accessible as an online resource and currently totals some 6.09GB of data and images. This paper details its findings, describes the specimen types, and gives a brief review of the sources of many of the specimens and the collectors who collected them.