A series of new Mannich bases 4a-i has been synthesized via a two-step procedure. Firstly, the Claisen-Schmitdt reaction of 4-hydroxyacetophenone (1) with 4-chlorobenzaldehyde (2) in ethanol at room temperature gave chalcone 3 in high yield. This compound was then reacted with paraformaldehyde and different sencondary amines in ethanol under reflux to afford a series of new Mannich bases in moderate to good yields. All synthesized compounds were structurally characterized by spectroscopic methods: IR, NMR and HR-MS. The antibacterial activity results showed that most of the compounds exhibited no activity against bacterial strains tested except the compound 4c, which exhibited significant activity against Staphylococcus aureus strain with IC50 values of 14.26 ug/ml.