The species diversity, chorology, and biogeography of the Steninae MacLeay, 1825 (Coleoptera: Staphylinidae) in Iran is described. A total of 68 species of Stenus Latreille, 1797 and one species of Dianous Leach, 1819 is recorded for this Middle Eastern country. Dianous coerulescens korgei Puthz, 2002, Stenus bicornis Puthz, 1972, S. butrintensis Smetana, 1959, S. cicindeloides Schaller, 1783, S. comma comma Le Conte, 1863, and S. hospes Erichson, 1840 are recorded for the Iranian fauna for the first time. Records of S. cordatoides Puthz, 1972, S. guttula P. Müller 1821, S. melanarius melanarius Stephens, 1833, S. planifrons planifrons Rey, 1884, S. pusillus Stephens, 1833, and S. umbricus Baudi di Selve, 1870 for Iran are, however, implausible or proved erroneous. Based on literature records and recent collecting data since 2004, the distribution of the stenine species in Iran is mapped, and their biogeographical relationships are discussed. As far as possible, the species are attributed to the commonly accepted distribution types in the Palaearctic Region after the theory of Pleistocene refuges of the arboreal biota. With the example of the Steninae and Scopaeus Erichson, 1839 (Staphylinidae: Paederinae), a cluster analysis is performed to examine the similarity of commonly accepted geographical units of Iran. The similar biogeographic pattern of the Steninae and Scopaeus reveal the high impact of Mediterranean elements on the fauna of Iran. The Hyrcanian subregion of the Caspian refuge is identified as the most significant center of origin of Stenus in Iran.