Utahraptor is the largest member of the dinosaur family DromaeosauriDae and represents one of the most remarkable discoveries in recent decades. In the original description, the specific epithet ostrommaysi was used for naming the species in honor of two different persons, but in subsequent years the spelling ostrommaysorum was often used without comment or explanation. In this paper, we review the historical uses of the specific epithet of Utahraptor and make clarifications on the status of six different subsequent spellings. The International Code of Zoological Nomenclature (1999) does not offer any provision for forming a genitive form from two persons having different names, so the original spelling ostrommaysi has to be regarded as an arbitrary combination of letters, and not a correctly formed genitive form. For this reason, it is deemed to be preserved unaltered and is not subject to a justified emendation; consequently, the subsequent spelling ostrommaysorum is erroneous and represents an unjustified emendation and shown not to be in prevailing usage. Therefore, the name to be used for the taxon is Utahraptor ostrommaysi, as originally introduced.