The aim of the present pilot study was to apply a flow cytometric assay, the so-called OxyDNA test, to determine the level of oxidative DNA damage in fish spermatozoa exposed to different concentrations (0.01–10,000 mg/L) of cadmium. Milt was collected from three randomly selected Prussian carp (Carassius auratus gibelio) males. Oxidative DNA damage was assessed with the OxyDNA kit and using flow cytometry. The ratio of OxyDNA-positive events increased significantly at higher cadmium concentrations. The results indicate that direct contact of fish spermatozoa with cadmium-polluted water initiates genotoxic damage.