With the daily application of a wide range of compounds from the group of pharmaceuticals and pesticides, they continuously reach the environment, primarily surface waters, where, despite low concentrations, they pose a danger to the living world. Designed to be persistent and biologically active, pharmaceuticals and pesticides bioaccumulate in aquatic ecosystems, where they show various toxic effects on certain populations of organisms, or give degradation and transformation products, often more toxic than the starting compounds. Although there are clear indications of their acute and chronic effect on the ecosystem, these compounds, as well as the other micro-pollutants, are often not monitored, so their actual effect has not yet been sufficiently investigated. For this purpose, various ecotoxicity tests are performed, and one of the methods is the test on freshwater crustacean Daphnia magna. The aim of this study was to examine the toxicity of 3 pharmaceuticals and 3 pesticides using the Daphnia magna freshwater crustacean method. For this purpose, an acute toxicity test was performed according to the HRN EN ISO 6341:2013 standard, while 6 model solutions of individual components and 18 binary mixtures of pharmaceuticals and pesticides were tested. The initial concentration of the solutions was 50 μM and a geometric series of dilutions was examined during the test. Results were recorded after 24 and 48 h. As additional factors, the values of the environmental indicators COD and BOD5 were examined. Inhibition values for individual components and mixtures are high at a concentration of 50 μM and fall suddenly at the next concentration (25 μM). Although this response makes sense, as it indicates a significant toxicity of 50 μM and above, EC50 values range from 1-10 μM and thus indicate a very high toxicity of these compounds and a high risk for the environment. Such deviation between inhibition and post-linearization results is probably caused by the inevitable linearization error. The tested compounds and mixtures are not biodegradable, which can be correlated with their high toxicity, but no other more significant correlation can be established. Since described values do not give a clear picture of toxicity and environmental risk, there remains a lot of space for further research, including the possible repetition of the carried out experiment with higher concentrations.