We recently reported that a genetic transformation of the RNA-Binding-Protein (McRBP), an RNA chaperone gene derived from common ice plant (Mesembryanthemum crystallinum), alleviated injury and loss of biomass production by salt stress in Eucalyptus camaldulensis in a semi-confined screen house trial. In this study, we assessed the potential environmental impact of the transgenic Eucalyptus in a manner complying with Japanese biosafety regulatory framework required for getting permission for experimental confined field trials. Two kinds of bioassays for the effects of allelopathic activity on the growth of other plants, i.e., the sandwich assay and the succeeding crop assay, were performed for three transgenic lines and three non-transgenic lines. No significant differences were observed between transgenic and non-transgenic plants. No significant difference in the numbers of cultivable microorganisms analyzed by the spread plate method were observed among the six transgenic and non-transgenic lines. These results suggested that there is no significant difference in the potential impact on biodiversity between the transgenic McRBP-E. camaldulensis lines and their non-transgenic comparators.