The incidence of cancer has increased worldwide and hormone antagonists are a group of pharmaceuticals used in the treatment of breast cancer. It is well known, that most of the pharmaceuticals are only partially removed or transformed during traditional wastewater treatment processes and the residues enter the environment through wastewater effluents. In aquatic environment, these pharmaceuticals pose a risk, as they may cause adverse effects on development and reproduction of organisms. In this study, the presence of two hormone antagonists, letrozole and tamoxifen, in wastewater influent and effluent samples was determined. Ultraviolet (UV) treatment is widely used technique to disinfect wastewater and drinking water. The potential of UV irradiation to degrade these selected pharmaceuticals was also studied in laboratory conditions. Preliminary results show the presence of studied pharmaceuticals in wastewater samples at low ng/L levels. Tamoxifen showed high degradation rates in UV treatment, whereas letrozole seemed to be quite resistant. Further studies to determine the occurrence of studied pharmaceuticals in environment are in progress. The experiments to improve the UV treatment are also planned.