We isolated 71 slow-growing bacterial strains from nodules of 27 native leguminous plants species in Senegal (West-Africa) belonging to the genera Abrus, Alysicarpus, Bryaspis, Chamaecrista, Cassia, Crotalaria, Desmodium, Eriosema, Indigofera, Moghania, Rhynchosia, Sesbania, Tephrosia, and Zornia playing an ecological role and having agronomic potential in arid regions. The isolates were characterised by restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S rDNA and comparative SDS-PAGE of whole-cell proteins; reference strains of the different known rhizobial species and groups were included as references. We conclude that these nodule isolates are diverse, and form several phylogenetic subgroups inside Bradyrhizobium. Nodulation tests performed on 5 plant species demonstrated host specificity among the strains studied.