The diploma thesis deals with the influence of petroleum pollution on surface water. Contaminants of petroleum origin are among to frequent pollutants from anthropogenic activity. In addition to oils of petroleum origin, oils of synthetic and vegetable origins could also be contaminants in the environment too.Testing of properties of selected types of oils was performed with the help of ecotoxicological tests in sample of surface water contaminated by oil. Two mineral oils of petroleum origin (OT-HP 3, TIRMAN), one synthetic oil (HLP 46) and one vegetable oil (BIOPLUS) were used for testing. To evaluate the oil properties which acts as contaminants in surface water were used these tests: the test of acute toxicity on Dafnia magna daphnias, the tests of inhibition of growth of Sinapis alba root, the inhibition of growth of green alga Scenedesmus subspicatus and duckweed Lemna minor. The software STATISTICA 10, ANOVA – single factor scattering analysis was used to evaluate the test results. The test of acute toxicity on daphnias revealed that TIRMAN oil has the most toxic effect on the aquatic environment from all of tested oils. Concentration of 0.3 grams per liter of water causes immobilization of 50 % of individuals. In the phytotoxic test with seeds of Sinapis alba, the toxic effect of mineral oils was higher in compared with synthetic and vegetable oils. In Scenedesmus subspicatus green alga tests was hard to distinguish the oil stains from the cells of the alga in Bürker´s box. So it was hard to count them under the microscope. But it was found a massive decrease of cells. In the test of inhibition of duckweed growth was found that mineral oils as contaminants in aquatic environment are more toxic than synthetic and vegetable oils.