Microplastics are any type of plastic particle that is less than 5 millimeters in length and it is released into the environment only as a result of the human behaviour. One of the ways to prevent the microplastics entering freshwaters is the use of wastewater treatment plants. They are highly efficient, but a lot of particles are still released into the environment. Most of the microplastics released into wastewaters are from personal care products (microbeads in peeling, toothpaste) and washing of synthetic clothes. When microplastics enter aquatic ecosystems, it can be ingested by various organisms and have negative impact on them. Microplastics can be also adsorbed on organisms, which is the major issue for low-density microplastics floating on the water surface and affecting floating plants. One of them is also common duckweed (Lemna minor). In the experimental work, we examined how the presence of microplastics affects the growth of the leaves and roots of the common duckweed. We prepared samples from three different types of plastisc (plastic bag, microplastics from cosmetics, shredded bakelite) and placed them together with the control samples in the incubator for seven days. The counting of roots and leaves and the measuring of the roots has led to the conclusion that microplastics negatively affects growth of roots and leaves.