Cytostatics are among the most dangerous substances, but still not much is known on their occurrence in the environment and effects on environmental organisms and human. Until now, they have been more or less overlooked, mostly because their consumption and the consequent environmental exposure to cytostatics is much smaller compared to other drugs. Studies in recent years show that drug residues in the environment can pose a serious threat to organisms in the environment and human health. However, the available information is insufficient to assess appropriate risk assessment and introduce appropriate protective measures. Therefore, the aim of our work was to determine the cytotoxic and genotoxic effects of four selected cytotstatics with different modes of action (5-fluorouracil, etoposide, cisplatin and imatinib mesylate) in fish liver cells ZFL. Cytotoxicity was determined with the MTT assay, genotoxicity with the comet assay. All used cytostatics induced time- and dose-dependent cytotoxic effects in ZFL cells, while in the cells, exposed to imatinib mesylate, we observed a specific threshold dose response at a concentration ~ 9:38 mg / mL at all exposure times. With the comet assay we have shown that all the cytostatics were genotoxic in a time- and dose-dependent manner. Since not much is known on the effects of these drugs on aquatic organisms, our results suggest that ZFL cells provide an important and sensitive tool for the assessment of genotoxic potential of environmental contaminants. However, for a more indepth knowledge of their adverse effects further studies on their cytotoxic and genotoxic activity are needed. The methods used in our study are the cost- and time- effective, while our results demonstrate that they are sufficiently sensitive for this kind of research.