Rhizobium strains isolated from Acacia farnesiana were positive for oxidase, catalase, urease, penicillinase and ?-galactosidase. The quantitative determination of enzymatic acti- vity indicated that these strains possessed 6-phosphogluconate dehydrogenase (6PGD) and ?- galactosidase activities but Bradyrhizobium japonicum didn't possess 6PGD and ?-galactosi- dase activities. Six strains isolated from A. farnesiana may be divided into two groups according to esterase pattern on PAGE: strains AF 1, AF2 and AF3' possessed A band on esterase pattern but strains AF4, AF5 and AF6 didn't.