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Bacteria with the ability to grow on nitrogen-free media and with nitrogenase activity were isolated from Salicornia plants, which it revealed for first time its association with this kind of microorganisms. Four areas were sampled to detect nitrogen-fixing bacteria associated with Salicornia rhyzosphere; from these, 21 colonies were isolated. Only one showed high acetylene reduction activity and capacity to solubilize phosphates. This bacterium was identified as Rhodococcus fascians. Our results suggest that Rhodococcus isolate have a particular affinity to growth at 0 to 0.75 M of NaCl and 30 to 55 degrees C. The effects of Rhodococcus fascians were evaluated in germination stage of Salicornia bigelovii SOS-7. This bacterium, in conjunction with Azospirillum halopraeferens, was tested for growth-promoting ability when inoculated on salicornia SOS-7 under various saline concentration conditions. During germination stage, Rhodococcus fascians showed high specificity to S. bigelovii SOS-7. This is the first report of R. fascians as a nitrogen-fixing bacterium associated with the halophyte Salicornia that they are developed growth in Bandar Abbas Iran desert. A reliable biological method, based on beneficial bacteria, suggested helping maintain or improve the fertility of soils to reproduce Salicornia SOS-7 as an important resource in many arid and semiarid regions of the world.