The objectives of this study were 1) to isolate and identify vesicular arbuscular mycorrhizal (VAM) fungi which were symbiotic with Amorpha fnsticosa L. 2) to select effective VAM fungi which can increase growth and phosphorus uptake of A. jruticosa, 3) to examine growth responses when inoculated singularly with VAM fungus or with their various combinations, and also when inoculated dually with various combinations of VAM fungi and Rhizobium. and 4) to determine optimum conditions for germination of isolated VAM fungal spores. VAM fungi and Rhizobinm were isolated from A. fruticosa and cultured using sudan grass and nutrient medium, respectively. The seedling inoculated with VAM fungi and/or Rhizobium were grown in the greenhouse or growth cabinets by cultivation technique using the concepts of Ingestadis steady state condition of nutrition. When harvested, growth, nitrogen and phosphorus concentration, chlorophyll content, photosynthetic ability and phosphatase activity in host plant, and infection rate and external hyphae of VAM fungi were measured. The results obtained from this study were as follows : 1) Four VAM fungi symbiotic with A. fruticosa were isolated. Two of them were identified as Gigaspora margarita Beck and Hall, and Scutellospore nigra Walker and Sanders ; unidentified ones were a Gigaspora sp. and a Glomus sp. 2) Scutellospora nigra and Gigaspora. sp, significantly increased the growth of A. fruticosa seedlings at low addition rates of phosphorus, whereas Gigasyora margarita did not. 3) Dual inoculation with VAM fungi and Rhizobium slightly increased the growth of A. fruticosa in the greenhouse. 4) The original soil from which VAM fungi were isolated, was most effective inoculum in this study. 5) External hyphal length was not affected by addition rates of phosphorus from 0% to 5%, but decreased abruptly at the 10% rate. 6) Root -shoot ratios were decreased with increasing addition rates of phosphorus after inoculation with VAM fungi. 7) Scrstellospora nagra cvas the most effective in uptake of phosphorus, and followed by Gigaspora sp. 8) The activities of alkaline and acid phosphatase were the lowest when inoculated with Scutellospora nigra, and Uigaspora sp., and their activities decreased with increasing addition rates of phosphorus. 9) There were synergistic or competitive interactions when inoculated with various combinations of VAM fungi. 10) The germination of isolated VAM fungal spores was high irrespective of environmental conditions. The germination was the highest in Gigaspora margarita, and followed by Gigaspora sp., and then Scutellospora nigra.