The genera Agrobacterium, Allorhizobium, and Rhizobium belong to the family Rhizobiaceae. However, theplacement of a phytopathogenic group of bacteria, the genus Agrobacterium, among the nitrogen-fixingbacteria and the unclear position of Rhizobium galegae have caused controversy in previous taxonomicstudies. To resolve uncertainties in the taxonomy and nomenclature within this family, the phylogeneticrelationships of generic members of Rhizobiaceae were studied, but with particular emphasis on the taxaincluded in Agrobacterium and the “R. galegae complex” (R. galegae and related taxa), using multilocussequence analysis (MLSA) of six protein-coding housekeeping genes among 114 rhizobial and agrobac-terial taxa. The results showed that R. galegae, R. vignae, R. huautlense, and R. alkalisoli formed a separateclade that clearly represented a new genus, for which the name Neorhizobium is proposed. Agrobacteriumwas shown to represent a separate cluster of mainly pathogenic taxa of the family Rhizobiaceae. A. vitisgrouped with Allorhizobium, distinct from Agrobacterium, and should be reclassified as Allorhizobium vitis,whereas Rhizobium rhizogenes was considered to be the proper name for former Agrobacterium rhizogenes.This phylogenetic study further indicated that the taxonomic status of several taxa could be resolved bythe creation of more novel genera.