Itemirus is known from a single small damaged fossil braincase or neurocranium, in 1958 found near the village of Itemir at the Dzharakuduk escarpment in layers of the Bissekty Formation. This holotype has accession number PIN 327/699. The type species, Itemirus medullaris, was named and described by Sergei Kurzanov in 1976. The generic name refers to Itemir. The specific name refers to the medulla oblongata, the brain part encased by the partial braincase.
Kurzanov noted anatomical similarities to the Tyrannosauridae and the Dromaeosauridae; he assigned Itemirus to a separate Itemiridae. In 2004 Thomas Holtz suggested it was a member of the Tyrannosauroidea. Nicholas Longrich and Philip J. Currie in 2009 included Itemirus in a cladistic analysis of internal dromaeosaurid relationships and found it to be a velociraptorine.
No other species have been permanently assigned to this genus. Since only the braincase was discovered, the only certain estimates concern its brain size, and evidence that it had good vision and balance, based on the large lobes of the brain.