In the present study some new mono- and bis- Mannich bases were synthesized, characterized and screened for their antimicrobial activity. These compounds were synthesized using a green and efficient free catalyst method by reacting 2-[1-(4-amino- phenyl)ethylidene]-5,5-dimethyl-cyclohexane-1,3-dione (dimedone - chalcone derivative) with formaldehyde and primary aromatic amines namely, 4-bromoaniline, 2-aminobenzo- thiazole, 4-chloroaniline and 2-aminophenol in a mono and double molar ratio. The preparation of Mannich bases aims to find some new compounds with hydrophilic nature and wide medicinal effects. The structures characterization was performed using IR, 1HNMR, 13CNMR, DEPT 135 NMR spectroscopy and elemental analyses. The activity of the synthesized compounds against bacteria, Gram-positive: Staphyllococcus aureus, Bacillus Subtilis and Gram-negative: Escherichia coli was determined by using the agar diffusion method. Significant activity for the synthesized compounds was observed against both of the Gram-positive and Gram-negative bacteria. Bis - Mannich bases 6a-c showed stronger antimicrobial effect more than mono - Mannich bases 5a-c. The compounds obtained are still the theme of pharmacological research.