OBJECTIVES: Bisphenol A (BPA) is an endocrine disruptor which has been shown to be a harmful compound for living organisms. It is the main component of the most commonly used plastic products such as plastic bottles, food cans and containers or dental fillings, and other medical aids. Recently, it has become a new environmental pollutant. The current knowledge about the BPA effects (including genotoxic one) on different cells is in many cases contradictory. Thus, the aim of the paper is to study the potential genotoxic effect of BPA. METHODS: An observation of the genotoxic activity of BPA on human lymphocytes was evaluated by using the alkaline comet assay and a modified comet assay with bacterial DNA repair enzyme Fpg. The potential DNA-protective effect of BPA was tested by using the DNA-topology assay. RESULTS: The results show that rising concentrations of BPA increase the risk of DNA double-strand breaks and modified purines in human lymphocytes. Interestingly, BPA shows an ability to protect plasmid DNA from the damage of iron ions in cell-free system. CONCLUSIONS: BPA itself does not induce genotoxic effect to DNA. However, BPA treatment of human lymphocytes leads to the induction of DNA damage. The proposed mechanism of BPA action in the human lymphocytes could be mediated by cell metabolism that induces an oxidative stress and ROS formation. ROS subsequently attack DNA and thus induce DNA damage. According to our results, BPA can be included in the group of substances with dual effects involving genotoxic and DNA-protective activity.