Evaluation of genetically modified plant varieties (before placing in culture) is generally focused on aspects of genetic stability of the inserted genes and agronomic aspects of GM varieties. However, in the international scientific community there is concern about the environmental consequences of introducing a functional gene associated with changes in management practices and agricultural systems on the essential functions of the ecosystem, and the fate of the products obtained from genetically modified organisms (GMOs) e.g. persistence in the environment and gene transfer to other organisms. These issues must be included in every study of risk assessment for GMOs. In Romania were not conducted studies and independent researches to assess the impact of cultivation of genetically modified plants on biodiversity, quality and functioning of agro ecosystems. Was studied, however, ecological and economic impact of the introduction into the environment of plants with a single genetically modified character, mainly glyphosate-tolerant soybean, cultivated in Romania until 2007 (Badea et al., 2004, 2006; Otiman et al., 2004). Soil biological communities are among the most diverse biotic groups on the planet. Soil microorganisms are involved in regulating a number of processes in terrestrial ecosystems, which are essential for maintaining its productivity and health. Develop methodology for assessing the Bt biotechnology impact, applied to cultivate genetically modified potato, on soil quality parameters, and particularly, on the microorganisms diversity, was done according to the following objectives: soil type influence (through its defining physical-chemical parameters) and genotypes of cultivated hybrids about insecticide persistence and degradation of proteins, influence of transgenic plants cultivation about microbial diversity, study of transgenic plant cultivars about the main soil chemical properties. The criteria for selection of soil materials on which to conduct the impact study of Bt biotechnology was favorability for species taken in the study and contrasting physical and chemical properties. Thus, were used two soil types: Eutric Fluvisols and Fluvi-Eutric Cambisols. Research developed in greenhouse has pursued: identifying correlations between the main physical-chemical and biological attributes of soil and plant genotypes (GMOs or non-GMOs) cultivation; environmental impact assessment of Bt protein on essential soil biological processes by investigating the biological activities associated with plant debris decomposition and determination of carbon, nitrogen, phosphorus and potassium in the soil; assessing the impact of Bt technology about taxonomic and genetic diversity of soil micro-organisms; assessment of possible modifications of the main physical, chemical and biological properties of soil under the influence of Bt technology.