Pollution of the aquatic environment by micro plastic could be having a massive impact on marine life. As far as the dimensions of the microplastics decrease, the negative effects are also increasing. In this study, the effects of 10-22 mu m diameter fluorescent polyethylene microplastics (PEMs) on Brachionus plicatilis and Daphnia magna were investigated. The acute toxicity and population growth test were conducted on Brachionus plicatilis. According to the tests LC50 value was calculated as 0.764 mg/mL (0.4-1.458, 95% confidence limits). Statistically significant differences were found in the 90 hour population growth test compared to the control. According to genotoxic evaluation on Daphnia magna with single cell gel electrophoresis (Comet), tail length, tail intensity and tail moment were increased by PEMs compared to the control. In conclusion, PEMs (10-22 mu m) have negative effects on both aquatic organisms Brachionus plicatilis and Daphnia magna.