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In Thailand, high arsenic concentrations have been found in many cultivated soils including on highland areas of northern Thailand. Arsenic is very toxic to plant and microorganism. Plants can uptake and accumulate arsenic in their tissues. Thus, a human health risk concern arises regarding accumulation of As in plant grown in these soils.  Five isolates (7, 8, 11, 19, 29) of arsenic-resistant bacteria that can transform arsenic to a less toxic form, were selected from our previous study.  In the present study, plant growth promotion potential of these isolates i.e. IAA production, phosphate solubilization, siderophores production and seed germination test was evaluated. IAA was determined using Salkovaski’s method; the results showed that isolate 19 and 11 performed highest IAA production in the medium with and without sodium arsenite and aluminum, with values of 20.32 and 18.41 mg/L, respectively. All isolates were able to acidify Pikovskaya’s medium while released Ca-phosphate into soluble P.  Isolate 7 showed the highest ability to solubilize phosphate both in Pikovskaya’s medium with and without sodium arsenite and aluminum (100.04 and 55.56 mg/L), respectively.  All isolates increased percentage of seed germination by 6.67 -16.67% over the control and isolate 29 showed the best performances (96.67% seed germination) to increase the seed germination.  So, these isolates may be employed as potential bio-inoculants for detoxifying arsenic and improving plant growth in arsenic contaminated soil.