Pesticides have an important role in protecting plants from various parasites and diseases. Unfortunately, parasites are very quick to produce resistance to the same, which leads to the use of more toxic pesticides, and thereby the greater environmental pollution, especially water. Considering the circulation of substances in nature and food chain participants, pesticides pose a great danger to humans and the rest of the plant and animal world. It is important to remove them from the environment, and among the effective methods of their removal we include reverse osmosis (RO) and nanofiltration (NF). In this work the efficacy and mechanism of removal of selected pesticides (thiamethoxam, imidacloprid, clotianidine, acetamiprid, thiacloprid, trialate, oxadiazone) from Watch list of substances for European union wide monitoring (Directive 2008/105/EC) from model waters with RO/NF membranes were investigated. Six NF (DK, HL, KH, DL, NF90, NF270) membranes were tested. The flux and pesticide retention were investigated. The effectiveness of removing pesticides depended on the pore size of the membrane, the interactions between pesticides and membranes, and the physicochemical characteristics of pesticides. From obtained results, it can be seen that the slight nanofiltration membranes DK, HL, DL and NF270 have the highest fluxes, and therefore the least retention factors. The DK membrane has shown a slightly smaller flux compared to the other slight membranes, and the reason is relatively low effective number of pores. The NF90 membrane, though dense in structure, proved to be good at large flux. Together with the KH membrane, the NF90 showed high retention factors and justified its dense structure.