The root-nodulating nitrogen-fixing bacteria are divided into fast growers (Rhizobizrm spp.) and slow growers (Bradyrhizobium juponicum), mainly on the basis of their growth rate, flagella and physiological characteristics such as utilization of, and production of alkali or acid on, various carbon sources (Allen and Allen 1950; Ian and Broughton 1981). However, fast growing BY. japonicum has been isolated from soybean root nodules from China (Keyser et al. 1982) and characterized as physiologically distinct from slow growing BY. juponicum. Furthermore, Stowers and Eaglesham (1983) reported a strain BTAi1 isolated from Aeschynomene which had characteristics of both fast and slow growing rhizobia. While studying microbial diversity at farm sites along the Tamil Nadu Coast in the South Arcot region, root-nodulating strains from Arachzs hypogaea, which revealed intermediate characters, were isolated. This paper describes investigations carried out on representative isolates, from each site, in relation to phenotypic features and RAPD profiles of the genomic DNA.