Microplastics are plastic particles smaller than 5 mm. Their occurrence in the environment has given a new concern about their impact on organisms an humans. It is known, that aquatic ecosystem is one of the most important ecosystem regarding occurrence of microplastics and its subsequent transport into marine environment. Waste water treatment plants are the main source of microplastic pollution in aquatic environments due to usage of microplastics in facial scrubbers and tooth paste and disintegration of synthetic clothes that cause generation of microplastics. Scientists are mainly focused on impact of microplastics on organism after ingestion. However, it is not known how microplastics affect freshwater plants. In our work toxicity tests with different types of microplastic (from cosmetics, plastic bag and bakelite) and natural particles on common duckweed Lemna minor were performed. Growth rate, root length and possible root damaging was observed. Microplastic does not impact the growth rate, but changes in root length was observed.