37 shipwrecks, constituting the biggest medieval shipwrecks collection in the world, which are dated from 5th to 11th centuries AD, were uncovered by salvage excavations conducted in Yenikapi, Istanbul. In this study, 160 wood samples taken from eight shipwrecks (YK 13, YK 16, YK 18, YK 21, YK 22, YK 25, YK 29 and YK 35) were analyzed for determining degradation degree of the woods. For this purpose, physical property analyses such as maximum water content, basic density, and loss of wood substance, and SEM-EDS were conducted. In order to examine the relationship between the degradation degree of the woods and wood species, samples were taken from different shipwrecks considering wood species. The wood samples were determined as 9 different species of wood (oak, pine, elm, cedar, cypress, ash, fir, plane and chestnut). Maximum water content values of the samples ranged between 148% and 1044%. With the evaluation of the highly degraded wood samples group, especially plane wood samples were found in this group.