The nano-ecotoxicological research is supported and promoted by European Commission. In 2005, the Action Plan “Nanosciences and nanotechnologies: An Action Plan for Europe 2005–2009” was adopted (European Commission, 2004). The European Commission clearly states the need for the new scientific experiments that will provide quantitative data on toxicology and ecotoxicology and allow for the risk assessments to be carried out on nanomaterials. In year 2006 the Chemicals Committee of the OECD has formed special Working Party on Manufactured Nanomaterials [WPMN]. One of the nanomaterials included in the OECD WPMN priority list is titanium dioxide (TiO2). Titanium dioxide nanoparticles (nano-TiO2) present the biggest ecotoxicological concern due to the rapid increase of anthropogenic input into the environment. Estimated environmental concentrations of nano-TiO2 in water range from 0.7 to 24.5 ng/mL.CURRENT AQUATIC EXOTOXICOLOGY TESTING OF NANO-TIO2 ARE NOT SUFFICIENT FOR THE RISK ASSESSMENT, as the testing is done by exposing the aquatic organisms to water suspension of nano-TiO2. Although the nano-TiO2 can be absorbed by the gills and skin of aquatic animals, the absorbed amount is insignificant compared to the potential of uptake through diet. Based on our previous research (Jovanovic et al., 2011, Jovanovic & Palic , 2012) we have classified nano-TiO2 as a potent immunotoxin, and there have been no previous studies that have investigated synergistic effects of nano-TiO2 during co-exposure to pathogenic bacteria. Therefore, we propose to use multidisciplinary approach by combining immunology assays, bacterial challenge studies, gross pathology of the brain, kidney and liver, and next generation deep gene sequencing - in order to determine toxicological effects and relevant biological targets upon acute exposure to nano-TiO2 through diet. Such study will provide regulatory agencies with long-time sought relevant ecotoxicological data for performing the risk assessment