The aim of the study was to evaluate the usefulness of Escherichia coli K-12 RFM 443 recA::lux for cytotoxicity and genotoxicity monitoring of metoprolol in the environment. Metoprolol is one of the most popular cardiac drug which belongs to the group of β-blockers. The drug was applied at the concentrations ranging from 0.01 µg/cm3 to 100 µg/cm3. The conducted research constitutes preliminary study aimed at validation of the recA::lux gene construct in order to determine its sensitivity to metoprolol. The drug concentrations were selected experimentally to obtain a positive luminescence response. The obtained data indicated the influence of metoprolol on lux gene expression and recA promoter activity based on the application of laboratory samples using PBS buffer. The results indicate a potential for using a bacterial biosensor Escherichia coli K-12 RFM 443 with recA::lux gene fusion in cytotoxicity and genotoxicity monitoring of the cardiac drugs residue in the environment.