A Gram-negative, rod-shaped bacterium was isolated from the skin of the medical leech Hirudo verbana and studied for its taxonomic allocation. 16S rRNA gene sequence similarities to other strains showed that the strain was closely related to species of the genus Kaistia. Kaistia geumhonensis was shown to be the most closely related species (96.8%), followed by Kaistia soli (96.6%) and Kaistia dalseonensis (96.2%). All other species of the genus Kaistia showed 16S rRNA gene sequence similarities <96%. Chemotaxonomic data for strain E94(T) (major ubiquinone: Q-10; major polar lipids: diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylserine, unknown phospholipids, aminolipids and aminophospholipids; and major fatty acids: C(18:1)ω7c, C(19:0)ω8c cylco, C(16:0) and C(18:0)) supported the affiliation of the isolate to the genus Kaistia. Phenotypic differentiation of strain E94(T) from all species of the genus Kaistia was possible using different physiological characters. Strain E94(T) represents a novel species of the genus Kaistia, for which the name Kaistia hirudinis sp. nov. is proposed, with the type strain E94(T) ( = LMG 26925(T) =CIP 110381(T) =CCM 8401(T)).