Microplastics is a pollutant which represent a growing threat to the environment. Plastic textile microfibers are the main source of microplastic accumulation, which is mostly released through the sewage sludge. In addition to this pollutant, there are other pollutants in the soil, such as plant protection products. Plastics is capable to adsorbe organic matter, therefore we wanted to determine the combined effect of microplastics and pesticides on terrestrial isopods Porcellio scaber. For 3 weeks terrestrial isopods were exposed to soil treated with insecticide chlorpyrifos (CPF) and combination of CPF and low (0.05 %) and high (0.5 %) concentrations of plastic textile microfibers (15 ̶ 1288 µm length). Mortality, feeding activity, biomass change and enzyme activity (acetylcholinesterase and glutathione S-transferase) of terrestrial isopods were monitored. The results showed that the plastic fibers themselves had no effect on crustaceans. CPF however, reduced the survival and activity of the enzymes and had no effect on the amount of consumed food and biomass change. After adding plastic microfibers to CPF, the mortality of test organisms decreased, however the amount of consumed food and biomass change has increased. We suppose that fibers reduced the availability of CPF to organisms, as the results of acetylcholinesterase activity measurements confirmed. Acetylcholinesterase was less inhibited in the presence of microfibers. We conclude that combined exposure of pesticide CPF and textile microfibers to terrestrial crustaceans has smaller effect than in the case of single exposure to the pesticide alone.