Clay and silt powders taken from Mesopotamian cuneiform tablets and their surface were examined for biological indicators (specifically, diatoms). The tablets are dated to the Third Dynasty of Ur and belong to the category of economic and administrative texts. Three diatom spe- cies, Nitzschia palea, Stephanodiscus minutulus and Discostella sp., were identified, though they were found in quite low densities. These species are very common in polluted/eutrophic water. Further studies are needed, however, to exclude the possibility that these diatoms are a result of later contamination, for instance via the subsequent burial of the tablets.