The main focus of this research was microplastic, the small plastic particles less than than 5 mm in diameter. Microplastics can also be obtained directly in the form of fibers from washing, as particles from cosmetic products or as by-product of larger plastic parts. In our thesis we wanted to prove, that the current concentration of microplastics in the environment (compost heap) has an impact on terrestrial organisms, in this case terrestrial isopod crustaceans, Porcelio scaber. We hypothesised, that microplastics would have an impact on feeding, as it acumulates in the gut. We also anticipated that this would reflect in altered digestive gland (hepatopancreas) energy reserves in terms of lipids, proteins and carbohydrates. Animals were exposed to food, contaminated with microplastics and maintained properly in Petri dish. Exposure lasted 14 days under standard laboratory conditions. We used environmentally relevant concentrations of microplastics in compost heap (4 mg microplastics/g dry food). We tested three types of plastics: isolated from the cosmetic product in two different fractions and isolated from PVC bags. Analysis showed that the tested concentrations of microplastics had no effect on feeding and energy reserves after 14 days of exposure. We suggest further research with larger concentrations of microplastics and prolonged exposure times.