A series of new Mannich bases was synthesized based on 3-(4-Hydroxy-phenyl)-1-(4-methoxyphenyl)-propenone, and evaluated for antibacterial and antifungal activity. New Mannich bases 4a-i were obtained in moderate to good yields via the reaction of the intermediate chalcone 3 with paraformaldehyde and different sencondary amines in ethanol under reflux for 24-36h. All synthesized compounds were structurally characterized by spectroscopic methods: IR, NMR and HRMS. The bio-assay results showed that most compounds showed weak activity against bacterial and fungal trains tested. Compound 4c and 4h exhibited significant activity against Staphylococcus aureus strain with IC50 values of 17,25 and 18,97 ug/mL respectively.