In a wide search program towards new and efficient antimicrobial agents, a series of 40 substituted chalcones have been synthesized and tested for their in vitro antibacterial and antifungal activities. The structures of these compounds have been investigated by nuclear magnetic resonance spectroscopy and mass spectrometry. Among the (E)-4-aminoalkylthiochalcones and (E)-4-aminoalkoxychalcones tested, compounds 7, 10, 11, 30 and 31 have exhibited good antibacterial property against Staphylococcus aureus, Enterococcus faecalis and Bacillus subtilis.