A synthetic review of the historical systematics of Dermanyssus Dugès, 1834 (Acari: Mesostigmata: Dermanyssidae) is provided. The classification at the specific level in this early genus has not really been clarified during more than a century despite its economic impact, and the history of the genus is complex and includes various stages. Moreover, Dermanyssus currently includes 23 species, whereas the last review took only 18 species into account. Changes in the species status and position in the genus Dermanyssus from 1834 until today are presented. The evolution of the generic definition is explored and compared with other genera of the group. How the discrimination between the different species evolved in the genus is also examined. Some difficulties in the specific definitions are discussed. A current diagnosis of the genus Dermanyssus is given. A table of the species included in this genus since its first description along with their respective current positions, a list of the currently included species in Dermanyssus with their hosts, and a world map presenting their geographic distribution are provided.